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

tests/unit/test_user_settings.py

@@ -0,0 +1,70 @@
+from __future__ import annotations
+
+import pytest
+
+from app.services.user_settings import (
+    DEFAULT_NAV_VISIBLE_PAGES,
+    UserSettingsServiceError,
+    parse_nav_visible_pages,
+    parse_request_delay_seconds,
+    parse_run_interval_minutes,
+)
+
+
+def test_parse_run_interval_minutes_accepts_valid_value() -> None:
+    assert parse_run_interval_minutes("30") == 30
+
+
+def test_parse_run_interval_minutes_rejects_below_minimum() -> None:
+    with pytest.raises(
+        UserSettingsServiceError,
+        match="Check interval must be at least 15 minutes.",
+    ):
+        parse_run_interval_minutes("14")
+
+
+def test_parse_request_delay_seconds_accepts_valid_value() -> None:
+    assert parse_request_delay_seconds("2") == 2
+
+
+def test_parse_request_delay_seconds_rejects_below_minimum() -> None:
+    with pytest.raises(
+        UserSettingsServiceError,
+        match="Request delay must be at least 2 seconds.",
+    ):
+        parse_request_delay_seconds("1")
+
+
+def test_parse_nav_visible_pages_accepts_valid_pages() -> None:
+    parsed = parse_nav_visible_pages(
+        [
+            "dashboard",
+            "scholars",
+            "publications",
+            "settings",
+            "runs",
+        ]
+    )
+    assert parsed == [
+        "dashboard",
+        "scholars",
+        "publications",
+        "settings",
+        "runs",
+    ]
+
+
+def test_parse_nav_visible_pages_rejects_missing_required_pages() -> None:
+    with pytest.raises(
+        UserSettingsServiceError,
+        match="Dashboard, Scholars, and Settings must remain visible.",
+    ):
+        parse_nav_visible_pages(["dashboard", "publications"])
+
+
+def test_parse_nav_visible_pages_rejects_unknown_page() -> None:
+    with pytest.raises(
+        UserSettingsServiceError,
+        match="Unsupported navigation page id: reports",
+    ):
+        parse_nav_visible_pages(DEFAULT_NAV_VISIBLE_PAGES + ["reports"])