feat(auth): authentication module with multi-tenant isolation (RFC-001)

Introduce an always-on auth layer with auto-created admin on first boot,
multi-tenant isolation for threads/stores, and a full setup/login flow.

Backend
- JWT access tokens with `ver` field for stale-token rejection; bump on
  password/email change
- Password hashing, HttpOnly+Secure cookies (Secure derived from request
  scheme at runtime)
- CSRF middleware covering both REST and LangGraph routes
- IP-based login rate limiting (5 attempts / 5-min lockout) with bounded
  dict growth and X-Forwarded-For bypass fix
- Multi-worker-safe admin auto-creation (single DB write, WAL once)
- needs_setup + token_version on User model; SQLite schema migration
- Thread/store isolation by owner; orphan thread migration on first admin
  registration
- thread_id validated as UUID to prevent log injection
- CLI tool to reset admin password
- Decorator-based authz module extracted from auth core

Frontend
- Login and setup pages with SSR guard for needs_setup flow
- Account settings page (change password / email)
- AuthProvider + route guards; skips redirect when no users registered
- i18n (en-US / zh-CN) for auth surfaces
- Typed auth API client; parseAuthError unwraps FastAPI detail envelope

Infra & tooling
- Unified `serve.sh` with gateway mode + auto dep install
- Public PyPI uv.toml pin for CI compatibility
- Regenerated uv.lock with public index

Tests
- HTTP vs HTTPS cookie security tests
- Auth middleware, rate limiter, CSRF, setup flow coverage

backend/tests/test_memory_prompt_injection.py

@@ -154,3 +154,22 @@ def test_format_memory_renders_correction_without_source_error_normally() -> Non
 
     assert "Use make dev for local development." in result
     assert "avoid:" not in result
+
+
+def test_format_memory_includes_long_term_background() -> None:
+    """longTermBackground in history must be injected into the prompt."""
+    memory_data = {
+        "user": {},
+        "history": {
+            "recentMonths": {"summary": "Recent activity summary"},
+            "earlierContext": {"summary": "Earlier context summary"},
+            "longTermBackground": {"summary": "Core expertise in distributed systems"},
+        },
+        "facts": [],
+    }
+
+    result = format_memory_for_injection(memory_data, max_tokens=2000)
+
+    assert "Background: Core expertise in distributed systems" in result
+    assert "Recent: Recent activity summary" in result
+    assert "Earlier: Earlier context summary" in result