fix(flyway): disable placeholder-replacement so V85 ckjia seed's ${ENV_VAR} survives intact

mateclaw-server/src/main/resources/application.yml

@@ -53,6 +53,14 @@ spring:
       - classpath:db/migration/h2
     validate-on-migrate: true
     clean-disabled: true
+    # Disable Flyway's built-in ${...} placeholder substitution. Some migrations
+    # (e.g. V85 ckjia MCP seed) intentionally store ${ENV_VAR} literals so that
+    # mateclaw's runtime header parser (McpClientManager.parseHeaders) can
+    # expand them at request time. Flyway would otherwise try to resolve those
+    # tokens at migration time and fail with "No value provided for placeholder".
+    # Safe to disable globally because no migration in this project relies on
+    # Flyway-side ${...} substitution.
+    placeholder-replacement: false
 
   h2:
     console: