Beta readiness: full API test suite, EAS build config, launch checklist

Takes V1 from code-complete toward the closed beta:

- Tests: the suite grows from 5 to 29. handler.test.ts covers route
  dispatch, guest device-id validation and user creation, JWT provider
  derivation, the paywall flag pass-through, free/premium mode
  selection, the assistant-final transcript rule (post-unlock delivery),
  the 402 abuse cap and its premium exemption, and purchase-verify
  validation. chat.test.ts covers structured-output parsing, premium
  masking of analysis_ready, the exact Responses API payload (knowledge
  base + strict JSON schema + the no-manufactured-suspense rule) and
  error handling. subscription.test.ts covers the Apple adapter
  (active/expired/wrong-product/sandbox retry on 21007) and the Google
  adapter (real RS256 JWT signing against a generated key, token
  exchange, expiry, 410-gone), with fetch and secrets mocked.
- EAS: apps/mobile/eas.json with development/preview/production
  profiles for TestFlight and Play internal-testing builds.
- LAUNCH.md: step-by-step path to 20-50 beta users — AWS deploy and
  secrets, migration, sign-in providers, store products at
  $5.99/$49.99, EAS builds, CI role, and the beta measurement plan
  (retention, dialogue depth, upgrade timing, tester interviews).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0118DaxZR36RpnY524vRqx3z

apps/mobile/eas.json

@@ -0,0 +1,21 @@
+{
+  "cli": {
+    "version": ">= 12.0.0",
+    "appVersionSource": "remote"
+  },
+  "build": {
+    "development": {
+      "developmentClient": true,
+      "distribution": "internal"
+    },
+    "preview": {
+      "distribution": "internal"
+    },
+    "production": {
+      "autoIncrement": true
+    }
+  },
+  "submit": {
+    "production": {}
+  }
+}