Fix BigInt crash in protocol parameter parsing, add docker-compose

Protocol parameter fields (minFeeA, minFeeB, maxTxSize, maxValSize)
lacked fallback defaults, causing "Cannot convert undefined to a BigInt"
when Lucid-Evolution processed them. Added safe defaults sourced from
Vector public testnet and updated deposit values to match. Made
lovelaceToAda() defensive against undefined/null. Added diagnostic
logging to getWalletInfo and getProtocolParameters error paths.

Converted Dockerfile to multi-stage build and added docker-compose.yml
with inline Vector testnet environment config.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -0,0 +1,12 @@
+services:
+  vector-mcp:
+    build: .
+    container_name: vector-mcp
+    restart: unless-stopped
+    ports:
+      - "127.0.0.1:3000:3000"
+    environment:
+      - VECTOR_OGMIOS_URL=https://ogmios.vector.testnet.apexfusion.org
+      - VECTOR_KOIOS_URL=https://v2.koios.vector.testnet.apexfusion.org/
+      - VECTOR_SUBMIT_URL=https://submit.vector.testnet.apexfusion.org/api/submit/tx
+      - VECTOR_EXPLORER_URL=https://vector.testnet.apexscan.org