Tokencore 2.0.1, monolith Docker/CI, external signing, DB token catalog

[GalaxySciTech]

Summary

This change completes the agreed plan for a single-module wallet service under src/, tokencore 2.0.1, operational Docker/CI alignment, and clearer extension points for multi-chain signing and configuration.

What changed

• Dependency: com.github.galaxyscitech:tokencore 2.0.0 → 2.0.1 in build.gradle.
• Build & deploy: Root Dockerfile (multi-stage bootJar), docker-compose.yml uses ./Dockerfile, GitHub Actions and GitLab CI build ./gradlew bootJar and artifact build/libs/*.jar. Removed the duplicate top-level wallet-webapi/ tree.
• Spring configuration: src/main/resources/application.yml now wires MySQL (DB_URL / DB_USERNAME / DB_PASSWORD), JPA (ddl-auto: none, batch hints), Caffeine cache, keystore env alignment, Actuator + Prometheus (spring-boot-starter-actuator, micrometer-registry-prometheus).
• SysConfigKey: Repaired a corrupted enum file and added scheduler keys plus ETH_GAS_FALLBACK_URL (optional HTTP JSON fallback when the node cannot serve eth_gasPrice).
• Signing: ChainSigningService routes BTC/ETH USDT signing through tokencore or an optional HTTP external signer when wallet_chain_config.signing_backend is EXTERNAL. New column documented in db/wallet_db.sql and optional migration db/002_wallet_chain_signing_backend.sql. WalletProperties binds wallet.signing, wallet.tokencore (ETH_SIGN_CHAIN_ID, BTC_SIGN_CHAIN_ID), and wallet.external-signer.
• HSM: HsmXServiceImpl supports EOS, DOGECOIN, FILECOIN import paths from tokencore 2.0.1; Bitcoin/ETH/USDT signing uses configurable chain id strings instead of hard-coded mainnet constants.
• RPC: RpcClient.getGasPrice no longer calls the defunct ethgasstation endpoint by default; RpcClient.bitcoinStyleRpc centralizes UTXO RPC selection; WalletXServiceImpl.getUtxos uses it.
• E2 token catalog: Removed enum TokenKey; TokenCatalogService reads distinct chains/symbols from the token table; BlockChainController.get_support_token uses it; CacheServiceImpl no longer auto-inserts rows from the removed enum.
• Package rename: com.wallet.webapi → com.wallet.api (directory src/main/kotlin/com/wallet/api/).
• Docs & scripts: README / README_CN / .env.example / build.sh / start.sh updated for the monolith layout.

Verification

• ./gradlew test and ./gradlew bootJar succeed locally.
• Docker image build was not executed in this environment because the docker CLI is unavailable; the Dockerfile follows the same Gradle stages as CI.

Follow-ups (optional)

• Run db/002_wallet_chain_signing_backend.sql on existing databases that were created before this PR.
• Document or implement a reference external signer service for {baseUrl}/v1/sign if teams want EXTERNAL signing without writing their own adapter.