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>

fusionagi/core/__init__.py

@@ -14,6 +14,7 @@ from fusionagi.core.head_orchestrator import (
     select_heads_for_complexity,
 )
 from fusionagi.core.json_file_backend import JsonFileBackend
+from fusionagi.core.memory_backend import InMemoryStateBackend
 from fusionagi.core.orchestrator import (
     VALID_STATE_TRANSITIONS,
     AgentProtocol,
@@ -21,7 +22,9 @@ from fusionagi.core.orchestrator import (
     Orchestrator,
 )
 from fusionagi.core.persistence import StateBackend
+from fusionagi.core.postgres_backend import PostgresStateBackend
 from fusionagi.core.scheduler import FallbackMode, Scheduler, SchedulerMode
+from fusionagi.core.sqlite_backend import SQLiteStateBackend
 from fusionagi.core.state_manager import StateManager
 from fusionagi.core.super_big_brain import (
     SuperBigBrainConfig,
@@ -35,6 +38,9 @@ __all__ = [
     "Orchestrator",
     "StateBackend",
     "JsonFileBackend",
+    "InMemoryStateBackend",
+    "PostgresStateBackend",
+    "SQLiteStateBackend",
     "InvalidStateTransitionError",
     "VALID_STATE_TRANSITIONS",
     "AgentProtocol",