chore(harness): make repository agent-ready

Add concise routed context, task-aware agent roles, focused skills, and structured learning promotion.\n\nUnify local development and workspace tooling, add layered test and E2E verification, harden MCP authentication, and gate deployment behind verification and explicit production promotion.

apps/mobile/AGENTS.md

@@ -0,0 +1,15 @@
+# Mobile application
+
+Expo React Native with Expo Router, Zustand, Supabase, RevenueCat, Firebase, and
+native iOS/Android targets.
+
+- Read `DESIGN.md` before UI changes.
+- Routes belong under `app`; feature logic belongs under `src/features`.
+- Reuse existing Zustand stores and clear user-scoped state during sign-out.
+- Check RevenueCat availability before native purchase operations.
+- Use `.maybeSingle()` when zero rows are valid and handle nullable profiles.
+- Keep route files thin; extract focused components/hooks when responsibilities
+  diverge rather than enforcing a mechanical line limit.
+- Add stable accessibility labels or `testID` values for critical interactions.
+- Verify focused Jest tests, typecheck, lint, then native/Expo behavior as risk
+  requires. UI work needs observable simulator evidence.