docs: add BLOCKERS.md documenting Task 1 status and questions

- Documents what was completed vs what needs verification
- Lists items requiring Android SDK to test (compilation, ktlint, tests)
- Raises 3 questions requiring human decision:
  1. Wallet scope (per-session vs app-wide)
  2. Key storage behavior on biometric changes
  3. Testnet vs mainnet for initial development

BLOCKERS.md

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+# BLOCKERS.md - Phase 1 Implementation Blockers
+
+## Task 1: Module Scaffolding
+
+### Completed
+- ✅ Module structure created (api/impl/test)
+- ✅ Metro DI setup following Element X patterns
+- ✅ WalletEntryPoint and WalletState APIs defined
+- ✅ PaymentFlowNode placeholder with Appyx navigation
+- ✅ FakeWalletEntryPoint for testing
+- ✅ Cardano client library dependencies added
+- ✅ ProGuard rules configured
+- ✅ Basic unit tests added
+- ✅ Pushed to Gitea phase1-dev branch
+
+### Not Verified (No Android SDK in build environment)
+- ⚠️ `./gradlew :features:wallet:impl:assemble` - compilation not tested
+- ⚠️ `./gradlew ktlintCheck --continue` - code style not verified
+- ⚠️ `./gradlew :features:wallet:impl:test` - unit tests not run
+
+### Action Required
+When a developer with Android SDK runs this code:
+1. Run `./gradlew :features:wallet:impl:assemble` to verify compilation
+2. Run `./gradlew ktlintCheck --continue` and fix any code style issues
+3. Run `./gradlew :features:wallet:impl:test` to verify tests pass
+
+## Questions Requiring Human Decision
+
+### Q1: Wallet Scope
+Currently using `SessionScope` for wallet bindings. Should wallets be:
+- Per-session (current implementation) - each Matrix account has its own wallet
+- App-wide (`AppScope`) - one wallet shared across Matrix accounts
+
+**Recommendation:** Per-session seems correct for a Matrix-integrated wallet.
+
+### Q2: Key Storage Location
+Currently planning to use `EncryptedSharedPreferences` with Android Keystore.
+- Should keys be tied to biometric enrollment? (invalidated if biometrics change)
+- Or should keys persist even after biometric changes?
+
+**Recommendation:** Keys should be invalidated on biometric changes for security.
+
+### Q3: Testnet vs Mainnet
+Phase 1 plan targets mainnet (`Constants.KOIOS_MAINNET_URL`).
+- Should we build testnet support initially for safer testing?
+- Or go straight to mainnet?
+
+**Recommendation:** Testnet first for safer development, easy switch to mainnet later.
+
+---
+*Last updated: 2026-03-27*