Add the native Hesychia Android client so the repo can build beyond the placeholder README.

docs/ADR-002-capacitor-coexistence.md

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+# ADR-002: Capacitor coexistence & Play application id
+
+- **Status:** Accepted (initial)
+- **Date:** 2026-08-05
+- **Context:** Epic chat_web_app#111 — package-name continuity matters for IAP + reviews.
+
+## Decision
+
+1. Native app **`applicationId` = `ai.hesychia.chat`** (same as Capacitor / `llm-fe/android`).
+2. Until native internal testing replaces Capacitor on Play:
+   - Capacitor remains interim Play track.
+   - Do **not** upload both Capacitor and native AABs under the same listing as competing “current” production binaries without a freeze plan.
+3. When native auth → chat → IAP path is green on internal testing:
+   - **Freeze** Capacitor Play uploads.
+   - Promote native AAB on the same listing (versionCode continues upward from Capacitor’s last upload).
+4. `beta` flavor uses `applicationIdSuffix = ".beta"` → `ai.hesychia.chat.beta` for side-by-side installs during development only (not the production listing).
+
+## Rationale
+
+Same application id preserves Play listing, reviews, and RevenueCat / Play Billing product bindings already tied to `ai.hesychia.chat`.
+
+## Rejected
+
+- New id (`ai.hesychia.chat.native`) then migrate users — splits listings, breaks IAP continuity, worse for reviews.
+
+## Open ops
+
+- Confirm last Capacitor `versionCode` before first native Play upload.
+- RevenueCat dashboard already includes package id `ai.hesychia.chat` (Capacitor path).
+- Capacitor shell in `llm-fe/android` stays for web mobile wrap until product sunsets it; document deprecation in `chat_web_app` when freeze date set.