feat: add license loading at startup from env var or file

- LicenseBeanConfig wires LicenseGate bean with startup validation
- Supports token from CAMELEER_LICENSE_TOKEN env var or CAMELEER_LICENSE_FILE path
- Falls back to open mode when no license or no public key configured
- Add license config properties to application.yml

cameleer3-server-app/src/main/resources/application.yml

@@ -41,6 +41,11 @@ cameleer:
     debounce-ms: ${CAMELEER_INDEXER_DEBOUNCE_MS:2000}
     queue-size: ${CAMELEER_INDEXER_QUEUE_SIZE:10000}
 
+license:
+  token: ${CAMELEER_LICENSE_TOKEN:}
+  file: ${CAMELEER_LICENSE_FILE:}
+  public-key: ${CAMELEER_LICENSE_PUBLIC_KEY:}
+
 security:
   access-token-expiry-ms: 3600000
   refresh-token-expiry-ms: 604800000