feat(#27): Set up consola logger, make use of log levels in backend and frontend

CLAUDE.md

@@ -639,6 +639,7 @@ Set in `nuxt.config.ts` → `runtimeConfig.public`:
 - `serverApiBaseUrl` - Direct backend URL (server-side)
 - `serverApiBasePath` - Backend API base path
 - `keycloakTokenUrl` - Keycloak token endpoint
+- `logLevel` - Frontend log level (Consola). Controlled via `NUXT_PUBLIC_LOG_LEVEL` (defaults: `debug` in dev, `warn` in prod)
 
 OAuth configuration (`runtimeConfig.oauth.keycloak`):
 - `clientId`, `clientSecret`, `realm`, `serverUrl`, `redirectURL`
@@ -652,6 +653,9 @@ Main config in `src/main/resources/application.yaml`:
 - Database connection (PostgreSQL)
 - Keycloak JWT validation
 - Server port (default: 8080)
+- Logging levels via env vars:
+  - `LOGGING_LEVEL_ROOT`
+  - `LOGGING_LEVEL_APP` for `com.betriebsratkanzlei.legalconsenthub`
 
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