Wire all integrations + production hardening: 15 recommendations

Integration & Wiring:
- useStore/useAppState wired into App.tsx (replaces 8 useState calls)
- React Router wired at app root (URL-based navigation)
- SparklineChart/MetricCard/BarChart integrated into Admin + Ethics pages
- useNotifications.handleWSEvent wired into WebSocket handler
- Notification center dropdown in header with unread badge
- Locale selector added to Settings page (6 languages)
- Dashboard data fetching with 10s polling into MetricCards
- File drag-and-drop support on chat area

Production Hardening:
- PostgresStateBackend with connection pooling (psycopg2)
- App lifespan wires backend from FUSIONAGI_DB_BACKEND env (memory|sqlite|postgres)
- Redis cache wired from FUSIONAGI_REDIS_URL env at startup
- Multi-process uvicorn config for horizontal scaling

Testing:
- Playwright visual regression tests (12 stories x 2 viewports)
- k6 load test script with ramp/spike/ramp-down stages
- 7 new Python tests (postgres fallback, app wiring)

575 Python tests + 45 frontend tests = 620 total, 0 ruff errors.

Co-Authored-By: Nakamoto, S <defi@defi-oracle.io>

tests/test_postgres_backend.py

@@ -0,0 +1,30 @@
+"""Tests for PostgresStateBackend graceful degradation.
+
+When psycopg2 is unavailable, all operations are no-ops.
+"""
+
+from fusionagi.core.postgres_backend import PostgresStateBackend
+from fusionagi.schemas.task import Task, TaskState
+
+
+def test_graceful_fallback_without_psycopg2():
+    """PostgresStateBackend should silently degrade when Postgres is unreachable."""
+    backend = PostgresStateBackend(dsn="postgresql://invalid:invalid@localhost:1/invalid")
+    assert backend._available is False
+
+    # All reads return None/empty
+    assert backend.get_task("t1") is None
+    assert backend.get_task_state("t1") is None
+    assert backend.get_trace("t1") == []
+    assert backend.list_tasks() == []
+    assert backend.count_tasks() == 0
+
+    # All writes are no-ops
+    backend.set_task(Task(task_id="t1", goal="test"))
+    backend.set_task_state("t1", TaskState.ACTIVE)
+    backend.append_trace("t1", {"step": 1})
+    assert backend.delete_task("t1") is False
+
+    # Close is safe
+    backend.close()
+    assert backend._available is False