Feature: Default / startup project, mode persistence, selectable log

[trailcode]

Summary

This work adds a bundled default .ezy that loads on startup, an optional user-specific startup project (Blender-style), correct persistence and restoration of UI mode in project files, startup diagnostics in the log panel, a selectable / copyable log (read-only multiline ImGui input), and CMake/copy/preload wiring for native and Emscripten builds. Documentation in usage.md describes the startup-project flow.

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What changed

Build & resources (CMakeLists.txt)

• Preload res/default.ezy into the Emscripten virtual FS (Release and Debug linker flags).
• Post-build copy of res/default.ezy next to the executable for native and Emscripten output (alongside existing res/ezycad_settings.json copy).

Bundled template (res/default.ezy)

• New committed default project (includes sample geometry, sketch, view block, mode).

Startup & user override (src/gui.cpp, src/gui.h, src/settings.cpp, src/settings.h)

• load_default_project_() after init: tries saved startup first, then res/default.ezy, with JSON validation and fallback messaging.
• User startup: startup.ezy under OS config dir (Windows %APPDATA%\EzyCad\, macOS ~/Library/Application Support/EzyCad/, Linux $XDG_CONFIG_HOME/EzyCad or ~/.config/EzyCad/); Emscripten: localStorage key ezycad_startup_ezy.
• Settings window: Startup project section — “Save current as startup project” / “Clear saved startup”.
• After loading a startup template, m_last_saved_path is cleared so Save does not target the startup file by default.
• on_file(..., announce_load) — startup loads use announce_load = false (no “Opened” toast).
• serialized_project_json_() — shared serialization for Save and save-startup (includes mode).
• Startup logging to the log panel (ASCII-only punctuation so the bundled font does not show ? for Unicode ellipsis/arrows).

Mode after open (src/occt_view.cpp, src/gui.cpp)

• Removed gui().set_mode(Mode::Normal) at end of Occt_view::load(), which previously overwrote mode restored from the file.
• on_file applies mode from JSON after m_view->load(); missing/invalid mode → Normal.

Log panel (src/gui.cpp, src/gui.h)

• Replaced per-line TextWrapped with a single InputTextMultiline buffer (read-only) for text selection and copy (Ctrl+C when focused).
• ImGuiInputTextFlags_CallbackAlways + small callback to scroll caret to end when new lines are appended.

Docs (usage.md)

• New “Startup project (defaults)” section (Settings-based workflow, paths, web storage).

Suggested testing

1. Clean profile: No startup.ezy / no localStorage entry — app loads res/default.ezy, log shows bundled path; mode matches file.
2. Save startup: Settings → save startup — restart — saved project loads; Save still prompts or uses last path only after a normal Open/Save-as.
3. Clear startup — next run uses bundled default again.
4. .ezy round-trip: Save with a non-Normal mode, reopen — mode restored.
5. Log: Select log text, copy with Ctrl+C.
6. Wasm: Preload present; startup from localStorage if set.
7. Native: POST_BUILD copy places res/default.ezy beside the binary; run CWD as build output (existing VS debug layout).

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Optional follow-ups

• Add trailing newline to res/default.ezy if tooling complains (\ No newline at end of file in diff).
• Consider factory reset that reloads bundled default in-session without restart.
• localStorage size limits for very large startup projects on web.

[trailcode]

Done