Sea orm integration

[dcorral]

Replaces file-based persistence with SQLite database using sea-orm ORM.

Changes

New database tables:

• mnemonic - encrypted mnemonic storage
• kv_store - LDK persistence (channel manager, payments, swaps, network graph, scorer)
• config - configuration key/value pairs (indexer_url, proxy_url, etc.)
• revoked_token - revoked auth token IDs
• channel_peer - channel peer pubkey/address mapping

Migrated to database:

• Mnemonic (was encrypted file)
• All LDK KVStore data (channel manager, inbound/outbound payments, swaps, scorer)
• Config parameters (synced to files for rust-lightning compatibility)
• Revoked tokens (was flat file)
• Channel peer data (was flat file)
• PSBTs (temporary storage during channel funding)
• Output spender transactions

Architecture:

• Single shared DatabaseConnection via Arc
• SeaOrmKvStore implements rust-lightning's KVStoreSync trait
• Migrations run automatically on startup
• Config stored in DB as source of truth, synced to files for rust-lightning compatibility