chore(quality): clear Sonar code smells and raise coverage to ~95.8%

[HandyS11]

Summary

Resolves the 4 open SonarQube code smells and lifts coverage from 89.8% → ~95.8% (line 91.8% → 97.4%, branch 84.1% → 91.6%; measured locally via opencover with the CI's sonar.coverage.exclusions).

Code smells (all in Lib.EntityFramework)

Rule	File	Fix
S1192	SqlColumnTypeMapper.cs	repeated "decimal" literal → Decimal const
S3776	FluentSyntax.cs	ResolveOwningEntity (cognitive complexity 22) split into ResolveFromReceiverChain / ResolveFromAncestors / ComposeOwnedKey
S107	FluentOwnedTypeWalker.cs	GetOrCreateOwned 8 params → 5 via OwnedTarget record
S107	EfModelAnalyzer.cs	ResolveOwnedNavigationTypesAsync 8 params → 3 via OwnedTypeResolutionContext record

All refactors are behavior-preserving; the S3776 split keeps each return in the receiver-chain loop terminal (including the UsingEntity → null case) by signalling "the chain settled it" rather than falling through to the ancestor search.

Bug fix (surfaced by new coverage)

FluentOwnedTypeWalker.ResolveOwnedType seeded zero columns for an OwnsMany over a T[] array navigation — its is not INamedTypeSymbol guard rejected IArrayTypeSymbol, even though the file-discovery path (OwnedClrTypeName) already unwraps T[] and documents it as supported. The seeding path now unwraps the array element type up front so both paths agree. Covered by a new test.

Coverage

15 new *CoverageTests.cs files (~207 tests) across CLI, MCP, Core, ClassDiagram and EntityFramework, targeting the worst-covered error/fallback paths (ErdCommand 60%, CollectingOutputConsole 44%, DiagramResourceCache 62%, CompilationFactory 69%, the EF fluent walkers, …).

Verification

• 1118 tests passing; build clean under TreatWarningsAsErrors + EnforceCodeStyleInBuild.
• The real Sonar quality-gate number re-evaluates on the develop push after merge (the sonarqube.yml workflow only triggers on push to develop, not on PRs).

Note (pre-existing, out of scope)

McpTransportTests.ListTools_OverRealStdioTransport_ExposesAllFourTools is flaky under full-suite parallel load (65s init timeout) but passes standalone in ~5s. Not touched here; worth a separate stabilization fix.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR focuses on improving code quality and resilience across ProjGraph (notably EF Fluent API analysis and MCP/CLI robustness) by clearing SonarQube smells, fixing an owned-type array edge case, and substantially expanding automated coverage for error/fallback paths.

Changes:

• Refactors EF Fluent API ownership resolution and owned-type handling to reduce complexity/parameter counts and fix OwnsMany over array navigations.
• Adds broad “coverage tests” suites across EF, Core, ClassDiagram, CLI, and MCP to exercise guard rails and degraded/fallback behavior.
• Adds renderer and discovery edge-case coverage to ensure diagrams remain valid under unexpected model states.

Reviewed changes

Copilot reviewed 19 out of 19 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/ProjGraph.Tests.Unit.EntityFramework/FluentWalkerCoverageTests.cs	New unit coverage for EF Fluent API walkers’ guard/fallback paths.
tests/ProjGraph.Tests.Unit.EntityFramework/FluentSyntaxCoverageTests.cs	New unit coverage for FluentSyntax receiver-chain/ancestor resolution and name extraction.
tests/ProjGraph.Tests.Unit.EntityFramework/EfRenderingCoverageTests.cs	New unit coverage for Mermaid ERD renderer defensive fallbacks.
tests/ProjGraph.Tests.Unit.EntityFramework/EfDiscoveryCoverageTests.cs	New unit coverage for EF file discovery boundaries and array-owned navigation discovery.
tests/ProjGraph.Tests.Unit.EntityFramework/EfAnalyzerCoverageTests.cs	New unit coverage for EF Roslyn analyzers on unusual attribute/type shapes.
tests/ProjGraph.Tests.Unit.Core/ProjectParserCoverageTests.cs	New unit coverage for malformed MSBuild inputs and property/version fallback logic.
tests/ProjGraph.Tests.Unit.Core/OutputConsoleCoverageTests.cs	New unit coverage for SpectreOutputConsole stdout/stderr routing and markup escaping.
tests/ProjGraph.Tests.Unit.Core/CompilationFactoryCoverageTests.cs	New unit coverage for compilation options, references, and cross-tree binding behavior.
tests/ProjGraph.Tests.Unit.ClassDiagram/ClassDiagramCoverageTests.cs	New unit coverage for class-diagram discovery/resolution fallbacks and renderer defaults.
tests/ProjGraph.Tests.Integration.Mcp/WorkspaceRootServiceTests.cs	New integration coverage for MCP workspace roots negotiation, caching, and invalidation.
tests/ProjGraph.Tests.Integration.Mcp/Helpers/InProcessMcpSession.cs	Adds in-memory client/server harness for MCP integration testing.
tests/ProjGraph.Tests.Integration.Mcp/DiagramResourceCacheTests.cs	New integration coverage for publishing/eviction/update notifications of cached MCP resources.
tests/ProjGraph.Tests.Integration.Mcp/CollectingOutputConsoleTests.cs	New coverage for MCP stdout-safe console warning buffering and async-flow isolation.
tests/ProjGraph.Tests.Integration.Cli/ErdCommandCoverageTests.cs	New CLI integration coverage for ERD discovery/prompting/non-interactive behavior and snapshot branch.
tests/ProjGraph.Tests.Integration.Cli/CommandOptionsCoverageTests.cs	New CLI integration coverage for validation/error reporting branches and DI adapter behavior.
src/ProjGraph.Lib.EntityFramework/Infrastructure/SqlColumnTypeMapper.cs	Removes repeated "decimal" literal via shared constant for Sonar smell cleanup.
src/ProjGraph.Lib.EntityFramework/Infrastructure/FluentSyntax.cs	Refactors ownership resolution to reduce cognitive complexity (receiver-chain vs ancestor search).
src/ProjGraph.Lib.EntityFramework/Infrastructure/FluentOwnedTypeWalker.cs	Refactors owned creation parameters and fixes OwnsMany array element-type seeding.
src/ProjGraph.Lib.EntityFramework/Infrastructure/EfModelAnalyzer.cs	Refactors owned-navigation resolution state into a context record to reduce parameter count.

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