feature: Integrate Tauri Decorum for custom window chrome

[jal-co]

Summary

Integrate tauri-plugin-decorum to manage a custom window frame/chrome while preserving the existing tabbed layout and general styling.

Tasks

• Add tauri-plugin-decorum dependency and configuration.
• Keep the current tabbed layout and remove the extra top/bottom bars in favor of unified chrome.
• Add light border/rounded edge styling via the plugin API to match the app’s theme.
• Investigate and address the previous macOS crash seen when testing decorum; document any fixes or workarounds.
• Verify window controls and drag regions still work; test on macOS (primary) and other supported platforms.

Notes

• Prior decorum attempt caused a macOS crash; stability is a key acceptance criterion.
• Maintain the Settings tab and existing UI while updating window chrome.

[jal-co]

Context gathered so far (no code yet):

• Current stack: Tauri 2.9.3, tauri.conf.json already sets decorations: false + titleBarStyle: "Overlay"; macOS signing/entitlements in place. Prior decorum attempt caused a macOS crash (null pointer in cocoa) which likely came from the decoration override path.
• Expected steps from the Decorum README pattern: add tauri-plugin-decorum dependency, register with tauri_plugin_decorum::init() in main.rs, and adjust tauri.conf.json window config to avoid conflicting decoration settings. Front-end needs a drag region (-webkit-app-region: drag) and no-drag on buttons/controls, since Decorum hands off the chrome.

Plan to make it happen:

1. Verify plugin compatibility matrix for Tauri 2.9.x and pick the matching decorum version (need README/release notes; I’ll check next).
2. Add the dependency and initialize in main.rs; keep other plugins untouched.
3. Reconcile window config: likely set decorations to false (or as required by Decorum) and remove conflicting titleBarStyle if the plugin owns the frame.
4. Front-end: ensure the TitleBar has drag regions and mark controls as no-drag; add a subtle border/radius to the main container to avoid the black square on dark backgrounds.
5. macOS stability pass: build/run locally, capture backtrace if the cocoa null pointer reappears, and adjust config accordingly.

Open questions to resolve via README/notes:

• Exact version of tauri-plugin-decorum compatible with Tauri 2.9.x.
• Any macOS-specific flags or known crash conditions (e.g., mixing titleBarStyle with plugin-driven decorations).

via codex