Fix Twilio MCP integration with baked-in credentials

- Add proper type and env sections to mcp-config.json
- Remove dynamic MCP add command, use pre-configured MCP
- Bake .env credentials into Docker image at build time
- Remove runtime .env volume mount - true one-time setup
- Auto-rebuild image when .env file changes
- Export Twilio env vars for MCP server subprocess
- Remove conflicting .mcp.json file

.gitignore

@@ -25,4 +25,6 @@ data/
 # Temporary files
 *.tmp
 *.temp
-~*
+~*
+# Environment file with credentials
+.env