feat(auth): implement API key authentication and management

Introduce a new API key authentication mechanism to support service-to-service
communication (e.g., Airflow, CI/CD) without browser-based JWT login.

- Add `APIKey` model and `APIKeyPrincipal` dependency for RBAC.
- Implement `require_api_key_or_jwt` dependency with environment scoping.
- Add admin CRUD endpoints for API key lifecycle management.
- Add API key management UI in System Settings.
- Update maintenance API to support explicit `environment_id` and API key auth.
- Add i18n support for API keys and connection settings.
- Include Python and Bash usage examples in the `examples/` directory.
- Update technical specifications and documentation.

.opencode/command/speckit.semantics.md

@@ -21,7 +21,6 @@ Ensure the repository adheres to the active GRACE semantic protocol using AXIOM
 3. **STRICT ADHERENCE** — follow the local semantic authorities:
       MANDATORY USE `skill({name="semantics-core"})`, 
       `skill({name="semantics-contracts"})`, 
-      `skill({name="semantics-belief"})`, 
       `skill({name="semantics-python"})`, 
       `skill({name="semantics-svelte"})`, 
       `skill({name="molecular-cot-logging"})`