chore: fix stale docs, add read_only to config example

- Update COMPONENT_AUDIT.md: replace htmx reference with React SPA
- Add server.read_only to config.example.yaml and CONFIGURATION.md

docs/CONFIGURATION.md

@@ -30,12 +30,14 @@ YAML values support environment variable expansion using `${VAR_NAME}` syntax. E
 | `server.host` | string | `"0.0.0.0"` | Bind address |
 | `server.port` | int | `8080` | HTTP port |
 | `server.base_url` | string | — | External URL (e.g. `https://silo.example.com`). Used for OIDC callback URLs and session cookie domain. Required when OIDC is enabled. |
+| `server.read_only` | bool | `false` | Start in read-only mode. All write endpoints return 503. Can be toggled at runtime with `SIGUSR1`. |
 
 ```yaml
 server:
   host: "0.0.0.0"
   port: 8080
   base_url: "https://silo.example.com"
+  read_only: false
 ```
 
 ---