feat: Add Monero wallet integration (Garnet merge - Phase 1-4)

Ported monero wallet infrastructure from Garnet fork with KMP adaptations:

    Quartz Events (KMP commonMain):
    - MoneroTipEvent.kt: Kind 1814 tip event with kotlinx.serialization, new
      async sign() API from NostrSigner
    - TipSplitSetup.kt: monero tag parsing extension functions for tip splits
    - EventFactory.kt: Registered MoneroTipEvent.KIND = 1814

    Model Layer (Android amethyst/src/main/java):
    - Wallet.kt: JNI wrapper around libmonerujo.so (~230 external calls)
    - WalletManager.kt: Wallet lifecycle factory (open/create/delete)
    - MoneroWalletListener.kt: Wallet lifecycle event interface
    - PendingTransaction.kt: JNI wrapper for pending tx creation
    - TransactionInfo/History.kt: Transaction history models
    - Subaddress, Transfer, ProofInfo: Supporting data classes

    Service Layer:
    - WalletService.kt: Android Service for wallet lifecycle (~700 lines)
    - MoneroDataSource.kt: Flow-based data source adapter
    - TipHandler.kt: Stub for tip orchestration
    - TipEventDataSource.kt: Stub for tip verification background processor

    Existing files modified:
    - Account.kt: Added moneroSpendKey/seed/restoreHeight/password flows,
      walletService binding, startMonero/stopMonero, balance getters,
      address validation, tip/sendMonero stubs
    - User.kt (commons): Added moneroAddress() method
    - UserMetadataCache.kt (commons): Added moneroAddressFromAbout() helper

    Resources & Build:
    - build.gradle.kts: Added MONERO_NETWORK buildConfigField
    - strings.xml: ~40 monero-specific strings added
    - monero.xml: Vector drawable icon

    Native Libraries:
    - monerujo.cpp/.h: C++ JNI bridge from Monero Rujoo wallet
    - wallet2_api.h: Monero wallet API header
    - .gitignore: Added jniLibs/*.so exclusion

    Build: Kotlin compilation passes (compileFdroidDebugKotlin)

README.md

@@ -477,6 +477,27 @@ By contributing to this repository, you agree to license your work under the MIT
   <img src="https://contrib.rocks/image?repo=vitorpamplona/amethyst" />
 </a>
 
+## Monero Integration Status
+
+An integration of Garnet's Monero tipping/zapping feature was attempted against the latest Amethyst codebase. The work lives on the `amethyst-with-monero` branch.
+
+**What was accomplished:**
+- Kotlin source code compiled successfully — `./gradlew compileFdroidDebugKotlin` passes
+- 21 new files added covering model, service, and account layers
+- Wallet key generation, service infrastructure, and account integration implemented
+
+**What's stubbed:**
+- `TipHandler` — placeholder implementations only
+- `TipEventDataSource` — not yet wired to the event layer
+- `MoneroDataSource` — pending full Monero node integration
+
+**What's next:**
+- Complete the UI layer for wallet display, transfer flows, and tip rendering
+- Implement the remaining stubbed methods on `Account`
+- Connect `TipHandler` to the existing NIP-57 zap machinery for parallel Lightning/monero support
+
+See [AGENTS.md](./AGENTS.md) for full project notes, build findings, and the merge plan.
+
 # MIT License
 
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