ff7a7d3b6b
SQLite wallet (default), RocksDB chaindb (default), Boost removal from common link, I2P startup performance fix (180s→27ms). Migration is automatic and non-destructive: - Wallet: BDB → SQLite on first open (original preserved as .bdb.bak) - ChainDB: LevelDB → RocksDB on next start (via -chaindb flag)