Add filter, virtualization, and export UI to DebugLogModal and unify file save

[jschick04]

Summary

Redesigns the debug log modal with filters, virtualized rendering, and export/copy actions, and unifies the existing file-save export pattern (used by 3 other modals) behind a new IFileSaveService.

Base branch: targets main. Diff is rendered against main.

What this changes

DebugLogModal redesign

• New DebugLogEntry record + DebugLogEntryParser parses [ISO-Timestamp] [ThreadId] [Level] message lines, folding continuation lines (stack traces) into the prior entry.
• New DebugLogProjection (pure) applies the active filters and reverses into newest-entry-first order via ReversedListView<T> (now implements IList<T> so Blazor <Virtualize> gets the Enumerable.Skip / Take indexer fast-path for deep offsets).
• Renders rows with <Virtualize> (RowHeightPx=18 initial estimate, monospace font, white-space: pre-wrap + overflow-wrap: anywhere so long lines and stack traces wrap within the viewport instead of forcing a horizontal scrollbar). Multi-line entries render across multiple visual lines, which makes <Virtualize>''s scroll-position math approximate for tall rows — accepted tradeoff vs. the prior nowrap+ellipsis approach (which was inaccessible to keyboard / touch users) and the prior horizontal-scroll approach (which the user explicitly disliked).
• Filter bar adds a level filter (ValueSelect with Equals / NotEqual / MultiSelect operators) and a debounced (250ms) message string filter.
• Footer adds Export to file, Copy to clipboard, and a centered X of Y entries counter.
• Refresh wraps the streaming LoadAsync in try/finally so partial data and _hasLoaded remain consistent on exception (generation-guarded).
• Clear awaits FileLogger.ClearAsync() first, mutates UI state only on success, surfaces failures via IAlertDialogService.
• DebugLogService.WriteTrace formats the timestamp inside _writeLock.EnterScope() so the on-disk line order is monotonic in timestamp under contention. Backed by a new Trace_WhenCalledFromMultipleThreadsConcurrently_* regression test that fires 64×4 parallel writes and asserts (a) line count, (b) every line parses, (c) timestamps non-decreasing, (d) every unique payload appears exactly once.

Unified file-save service

• New IFileSaveService (in EventLogExpert.UI.Interfaces) + FileSaveServiceFileTypes (Json / Log typed dicts) as the single source of truth for file-type choices.
• New MauiFileSaveService implementation registered in MauiProgram. Adds SetLength(0) before WriteAsync so overwriting a larger existing file no longer leaves stale trailing bytes (rationale documented inline).
• Refactors 3 pre-existing export sites (FilterGroup.ExportGroup, FilterCacheModal.OnExportAsync, FilterGroupModal.OnExportAsync) onto the new service, removing direct Windows.Storage.Pickers / WinRT.Interop dependencies from those razor.cs files.

Tests

• 20 DebugLogEntryParserTests (prefix parsing, continuation folding, malformed lines, no-prior-entry edge cases).
• 21 DebugLogProjectionTests (level operators, text filter case-insensitivity, ordering, empty filters).
• 28 DebugLogModalTests (bUnit) covering filter bar interactions, counter text, export call, clear success/failure, copy.
• 6 new ReversedListViewTests covering IndexOf (reversed semantics), Insert / RemoveAt / indexer setter throwing NotSupportedException, and the IList<T> interface assertion.
• 1 new DebugLogServiceTests concurrent-write regression test (64×4 parallel writers, four invariants).
• All 1870 tests pass; build clean (0 warnings).

Notes for reviewers

• MauiFileSaveService truncation order (SetLength(0) before WriteAsync) was deliberately chosen over a temp-file-and-rename pattern. Trade-off: a rare mid-write failure leaves a partial file on disk and surfaces the propagated exception (loudly visible) rather than the prior bug''s silent corruption (mix of new prefix + stale tail). Note this is not a temp-file-and-rename atomic write; partial-file-with-loud-failure is preferred over silent truncation-by-overwrite. Comment in source documents this.
• Clear() reorder is a small behavior change to a pre-existing path — file is now mutated before the UI, with explicit failure surfacing. Two new tests cover both branches.
• Sibling alert message inconsistency between DebugLogModal (ex.Message) and the 3 filter modals ($"An exception occurred while exporting X: {ex.Message}") is intentional — each surface describes its own context.
• Continuation-line ambiguity in DebugLogEntryParser is documented and intentional: the parser classifies any line matching the [ts] [tid] [Level] prefix as a new entry. A continuation line whose payload happens to start with that exact shape would be split as a new entry. Round 13 deliberately removed the previous timestamp-based heuristic because pre-PR-Add filter, virtualization, and export UI to DebugLogModal and unify file save #513 writers formatted the timestamp before acquiring the lock, so persisted legacy debug.log files can legitimately contain headers in non-chronological order — a timestamp-based heuristic that folded an "older-looking" header into the prior entry would corrupt those legacy logs. The format is inherently ambiguous when message bodies contain header-shaped lines; we accept that ambiguity (no current producer in this repo intentionally emits header-shaped continuation content) rather than corrupt legacy logs.

[Copilot]

Pull request overview

This PR redesigns the debug log experience in the components/UI layers by moving from raw line rendering to parsed entries plus filtered/virtualized projection, and it centralizes the app’s Windows file-save flow behind a reusable IFileSaveService. It fits into the ongoing component/library restructuring by keeping platform-specific save behavior in the MAUI head while letting lifted/shared UI code depend only on interfaces.

Changes:

• Adds structured debug-log parsing/projection primitives and rewires DebugLogModal to support level/text filtering, virtualization, export, copy, and improved clear/refresh behavior.
• Introduces IFileSaveService plus a MAUI/WinUI implementation, then refactors existing filter export paths to use it.
• Adds parser/projection/component tests and shared test constants/utilities for the new debug-log behavior.

Reviewed changes

Copilot reviewed 20 out of 20 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/EventLogExpert/wwwroot/css/app.css	Adjusts shared modal footer layout to support extra footer content.
src/EventLogExpert/Services/MauiFileSaveService.cs	Adds Windows MAUI implementation for unified text file saving.
src/EventLogExpert/MauiProgram.cs	Registers the new file-save service in DI.
src/EventLogExpert/Components/Modals/Filters/FilterGroupModal.razor.cs	Refactors saved-group export to use IFileSaveService.
src/EventLogExpert/Components/Modals/Filters/FilterGroup.razor.cs	Refactors single-group export to use IFileSaveService.
src/EventLogExpert/Components/Modals/Filters/FilterCacheModal.razor.cs	Refactors saved-filter export to use IFileSaveService.
src/EventLogExpert.UI/Services/DebugLogProjection.cs	Adds pure projection/filtering logic for parsed debug-log entries.
src/EventLogExpert.UI/Services/DebugLogEntryParser.cs	Adds parsing/folding of raw debug-log lines into structured entries.
src/EventLogExpert.UI/Models/DebugLogEntry.cs	Defines the structured debug-log entry record.
src/EventLogExpert.UI/Interfaces/IFileSaveService.cs	Introduces the shared file-save abstraction and common file-type maps.
src/EventLogExpert.UI.Tests/TestUtils/Constants/Constants.DebugLog.cs	Adds shared UI-test constants for debug-log parsing/projection tests.
src/EventLogExpert.UI.Tests/Services/DebugLogProjectionTests.cs	Covers projection ordering and filter behavior.
src/EventLogExpert.UI.Tests/Services/DebugLogEntryParserTests.cs	Covers parser prefix handling, malformed lines, and continuation folding.
src/EventLogExpert.Components/_Imports.razor	Imports Blazor virtualization support for components.
src/EventLogExpert.Components/Modals/DebugLogModal.razor.css	Styles the new filter bar, virtualized rows, and footer layout.
src/EventLogExpert.Components/Modals/DebugLogModal.razor.cs	Reworks modal state/behavior for parsing, filtering, export/copy, and refresh/clear flows.
src/EventLogExpert.Components/Modals/DebugLogModal.razor	Replaces raw line rendering with filter controls, Virtualize, and enhanced footer actions.
src/EventLogExpert.Components.Tests/TestUtils/DebugLogUtils.cs	Adds component-test helpers for building async debug-log data.
src/EventLogExpert.Components.Tests/TestUtils/Constants/Constants.DebugLog.cs	Adds shared component-test constants for debug-log modal tests.
src/EventLogExpert.Components.Tests/Modals/DebugLogModalTests.cs	Adds bUnit coverage for modal filtering, counter, export, copy, and clear behavior.

Comments suppressed due to low confidence (1)

src/EventLogExpert.Components/Modals/DebugLogModal.razor.cs:188

• LoadAsync() can still throw here (for example on access or read failures), and with only a try/finally the exception will bubble out of the event/lifecycle handler. That means opening or refreshing the modal can still fail as an unhandled UI exception instead of surfacing a recoverable alert like Clear/Export do.

        try
        {
            await foreach (var line in FileLogger.LoadAsync())

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