docs: document mobile comfort overhaul

Update codebase summary, system architecture, changelog, roadmap and
PDR to cover the new mobile input layer, haptics, gesture blocking
and PWA. Refresh README features. Add the brainstorm, plan and review
artifacts under plans/.

docs/development-roadmap.md

@@ -22,14 +22,20 @@
 - Drop dead Arcade physics and broken shutdown code.
 - Docs folder + README refresh.
 
-## Phase 3 — Polish (planned)
+## Phase 3 — Mobile Comfort & PWA (complete, 2026-04-27)
+- On-screen D-pad + thumb-zone action stack (hidden on desktop, visible on touch).
+- Browser gesture blocking (pull-to-refresh, double-tap zoom, long-press select).
+- Safe-area insets for notches and nav bars.
+- Haptics module (vibrate on box push + win).
+- PWA full offline support with Workbox service worker and installable Web Manifest.
+
+## Phase 4 — Polish (planned)
 - Sound effects (step, push, win).
 - Player facing direction indicator.
 - Level category tabs (Easy / Medium / Hard) derived from puzzle size or move count.
-- Touch controls (swipe) for mobile.
 - Unit tests for `level-parser` and `board-model`.
 
-## Phase 4 — Stretch (ideas)
+## Phase 5 — Stretch (ideas)
 - Additional level packs (Sasquatch, Sokogen).
 - Custom level importer (paste XSB text).
 - Replay / move playback.