feat(ui): mobile UI v2 — contrast, avatars, room-list density, compose FAB, gradient login (v1.8.0+12)

From a 7-agent design workflow (3 lenses judged + synthesised). Shipped the
high-impact/low-risk tier:
- message bubbles: self #1265ED (WCAG AA pass), incoming #1C2452 + hairline
- deterministic per-user avatar colours (8-hue brand palette)
- room tile: brighter unread preview, compact density, aligned timestamp
- FAB -> New message (thumb zone), explore -> AppBar
- login + welcome brand gradient, card outlines
- input maxLines cap, bubble max-width viewport fraction, AppBar hairline

All verified on production build in headless Chromium at mobile size.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

help4bis-claude-notes/decisions.md

@@ -91,3 +91,18 @@
 - **P5 Panic button:** NEW feature/panic module. Config in account data au.m8chat.panic (room + message). Hold-to-fire button in rooms AppBar (only shows when armed); Profile tile to arm/disarm. Alert text sent FIRST, then best-effort m.location pin (geo: uri, msc3488) with 10s geolocation budget so a denied permission never blocks the alert. VERIFIED end-to-end: text + location with exact GPS landed in the target room via mock geolocation.
 - **Status:** built, deployed app2.m8chat.au v1.7.0+11 (backup pre170 tarball on server). Analyze clean, tests pass.
 - **Deferred:** ghost-device cleanup, rooms-provider rebuild perf, native session persistence — still open from original notes.
+
+### 2026-07-04 07:50 — Mobile UI v2 design pass (v1.8.0+12)
+- **Process:** ran a 7-agent design workflow (3 lens designers: information-density, reachability-flow, polish-delight; 3 judges; 1 synthesiser). All proposals scored 8-9/10. Output: prioritised spec (A high-impact/low-risk, B medium, C defer). Full spec archived in session.
+- **Implemented the whole A tier + safe B items:**
+  - A1/A2 message bubble contrast: self #1265ED (selfBubble token, WCAG AA 5.11:1 vs failing 3.32:1), incoming #1C2452 + hairline border.
+  - A3 replaced failing low-alpha read text with subtleText token (rooms empty state, room tile).
+  - A4 deterministic per-user avatar colour (8-hue brand palette, name.hashCode) in matrix_avatar.dart — every disc now distinct.
+  - A5/A6 room tile: unread preview brightened+w500, compact density, timestamp aligned to title, unread dot spacing.
+  - A7 fixed stale "pencil icon" empty-state copy.
+  - A9 FAB now "New message" (compose) in thumb zone; explore moved to AppBar compass. Straight onPressed swap.
+  - A8 login + welcome brand gradient (#0A0F2E→#131A42), card hairline outlines.
+  - B7 message input capped minLines 1 / maxLines 6. B8 bubble maxWidth = viewport*0.78 clamped 560. B10 AppBar scrolledUnderElevation + hairline.
+- **Deferred (documented in spec):** B1 message grouping, B2 day separators, B4 quick-reaction row, B5 panic hold-ring, B6 scroll-to-latest FAB, C1 swipe-to-reply (iOS PWA back-gesture risk), C2 group sender prefix (needs RoomModel field), C3 demote Help nav.
+- **Verified:** headless Chromium at 390x844 on production build — gradient login, distinct avatar colours, compose FAB, AA bubble contrast all confirmed.
+- **Status:** built + deployed app2.m8chat.au v1.8.0+12 (backup pre180 tarball). Analyze clean, tests pass.