feat: production-harden app and finalize merge-ready UX/theme baseline

- complete tokenized theme preset system and admin style guide visibility
- refine dashboard layout/scroll behavior and shared async/request UI states
- add user nav-visibility settings across API, migration, and frontend stores
- harden security headers/CSP handling and related test coverage
- enforce CI repository hygiene + frontend contract/theme/build quality gates
- update docs/env references and make migration smoke test head-aware

app/api/schemas.py

@@ -433,6 +433,7 @@ class SettingsData(BaseModel):
     auto_run_enabled: bool
     run_interval_minutes: int
     request_delay_seconds: int
+    nav_visible_pages: list[str]
 
     model_config = ConfigDict(extra="forbid")
 
@@ -448,6 +449,7 @@ class SettingsUpdateRequest(BaseModel):
     auto_run_enabled: bool
     run_interval_minutes: int
     request_delay_seconds: int
+    nav_visible_pages: list[str] | None = None
 
     model_config = ConfigDict(extra="forbid")