Merge remote-tracking branch 'origin/dev' into fix/editor-followups-20261030

Reconcile branch with current dev (bebf53be).
Resolve conflicts in static/sw.js (bump cache version and preserve panel precache)
and src/ai_interaction.py (preserve upstream quality handling with per-user settings).

Remediate PR #6992 findings:
- A (CI & Playwright): Pin playwright==1.62.0 in requirements-dev and CI workflow; guard browser test imports against pytest runner collection failure.
- B (Per-User Image Model Settings): Support per-user image_model and image_edit_model in editor_image_models() and ai_interaction; enable non-admin preference persistence via /api/prefs fallback.
- C (CodeQL Regex Alert 1212): Replace polynomial-backtracking regex in routes/editor_agent_routes.py with linear token-based intent matcher.
- D (Undo/Redo rembg layer): Clear stale rembgLiveLayer and rembgLiveSnap references in _restoreState() to prevent edge tuner from corrupting detached layers.

requirements-dev.txt

@@ -2,3 +2,4 @@
 -r requirements.txt
 # psutil lets `-n auto` use physical cores instead of logical CPU threads.
 pytest-xdist[psutil]>=3.8,<4
+playwright==1.62.0