chore: prepare automation loop for Plan 2 (M8–M20)

- Add PLAN2.md with 116 tasks across M8–M20 with testing gates
- Populate loop/plan.md with all new tasks (30-attempt retry policy)
- Update loop/prompt.md to enforce glass design system and PLAN2.md
- Fix PassphraseDialog to use glass-card/gradient-button design system
- Fix crypto.randomUUID fallback for non-secure contexts
- Fix dev.sh to skip proxy startup if port 3141 already in use
- Fix PWA manifest for Android A2HS (purpose:any, display_override, id)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

PROGRESS.md

@@ -1,8 +1,8 @@
 # AIUI Progress
 
 ## Current Status
-**Active Milestone**: All milestones M1–M7 complete (except M1.5 E2E tests)
-**Overall**: ~95% architectural completeness
+**Active Milestone**: M8 — Chat UX Polish (PLAN2.md)
+**Overall**: M0–M7 complete. 116 tasks planned across M8–M20 in PLAN2.md
 
 ## Roadmap