feat: add schedule import functionality and quality control page

- Implemented the schedule import feature with a dedicated page for importing schedules from the transport website.
- Added a new QualityPage to check the quality of routes, stops, schedules, and notifications without making automatic changes.
- Created CSS styles for both the ScheduleImportPage and QualityPage to enhance the user interface.
- Introduced API calls for fetching schedule data and quality reports.
- Added error handling and loading states for better user experience during data fetching.
- Included functionality for filtering quality issues and displaying detailed reports.

backend/migrations/008_schedule_imports.sql

@@ -0,0 +1,24 @@
+-- Import previews are immutable snapshots; applying one is an explicit admin action.
+CREATE TABLE IF NOT EXISTS schedule_imports (
+    id UUID PRIMARY KEY,
+    route_id INTEGER REFERENCES routes(id) ON DELETE SET NULL,
+    source_url TEXT NOT NULL,
+    source_hash TEXT NOT NULL,
+    source JSONB NOT NULL,
+    status TEXT NOT NULL CHECK (status IN ('inspection', 'ready', 'applied')),
+    payload JSONB,
+    created_by INTEGER,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    applied_at TIMESTAMPTZ
+);
+CREATE INDEX IF NOT EXISTS idx_schedule_imports_created ON schedule_imports(created_at DESC);
+
+CREATE TABLE IF NOT EXISTS schedule_import_news (
+    url TEXT PRIMARY KEY,
+    title TEXT NOT NULL,
+    published_date TEXT,
+    content TEXT NOT NULL,
+    content_hash TEXT NOT NULL,
+    reviewed_hash TEXT,
+    checked_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);

backend/migrations/009_alert_scheduling.sql

@@ -0,0 +1,19 @@
+-- Delivery state is separate from visibility. A scheduled alert becomes visible
+-- at start_time; this state makes sure its push notification is sent once.
+ALTER TABLE alerts
+    ADD COLUMN IF NOT EXISTS notification_sent_at TIMESTAMPTZ,
+    ADD COLUMN IF NOT EXISTS notification_claimed_at TIMESTAMPTZ,
+    ADD COLUMN IF NOT EXISTS notification_attempts INTEGER NOT NULL DEFAULT 0;
+
+CREATE INDEX IF NOT EXISTS idx_alerts_pending_notification
+    ON alerts (start_time)
+    WHERE is_active = true AND notification_sent_at IS NULL;
+
+-- Earlier versions sent every active alert immediately on creation. Mark those
+-- already-created future alerts as dispatched, so upgrading does not notify
+-- passengers a second time when the scheduler starts.
+UPDATE alerts
+SET notification_sent_at = created_at
+WHERE notification_sent_at IS NULL
+  AND is_active = true
+  AND start_time > created_at;