docs: update all project docs to reflect Phase 8 + Android work

- CLAUDE.md unified-3.1 → unified-4.0: narrowed error policy, relaxed
  ECS/embed/API rules, added Android pitfalls, modal conventions (§14),
  Android build guide (§15), context injection system (§16), auto-hide
  HUD chrome exception in UI-first rule
- ARCHITECTURE.md: Android → Active platform; add Android to sync table;
  add SafeAreaInsets + HudVisibility to Key Resources; add solitaire_wasm
- CLAUDE_SPEC.md: add solitaire_wasm crate; communication: events → events and resources
- CLAUDE_PROMPT_PACK.md: fix §8 typo; narrow dep rule to core/sync only
- SESSION_HANDOFF.md: add §5b Android UX punch list; resume prompt unified-4.0
- docs/android/PLAYABILITY_TODO.md: add P5 section (UX-1/UX-5b/UX-7/BUG-3)
- docs/SESSION_HANDOFF.md: mark as archived (Phase 2 era)

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

CLAUDE_PROMPT_PACK.md

@@ -12,7 +12,7 @@ You must follow CLAUDE_SPEC.md strictly.
 Rules:
 - Do not expand scope beyond what is defined
 - Do not refactor unrelated code
-- Do not introduce new dependencies
+- Do not introduce new dependencies to solitaire_core or solitaire_sync without confirmation
 - Prefer minimal, surgical changes
 - Use existing patterns in the codebase
 - Return minimal diffs or changed functions only
@@ -360,7 +360,7 @@ notes:
 target:
 "<what is slow>"
 
-constraints:CLAUDE_WORKFLOW.md
+constraints:
 - no behavior change
 - no architecture change
 - minimal code changes