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/packages/harness/deerflow/config/skills_config.py

@@ -3,6 +3,11 @@ from pathlib import Path
 from pydantic import BaseModel, Field
 
 
+def _default_repo_root() -> Path:
+    """Resolve the repo root without relying on the current working directory."""
+    return Path(__file__).resolve().parents[5]
+
+
 class SkillsConfig(BaseModel):
     """Configuration for skills system"""
 
@@ -26,8 +31,8 @@ class SkillsConfig(BaseModel):
             # Use configured path (can be absolute or relative)
             path = Path(self.path)
             if not path.is_absolute():
-                # If relative, resolve from current working directory
-                path = Path.cwd() / path
+                # If relative, resolve from the repo root for deterministic behavior.
+                path = _default_repo_root() / path
             return path.resolve()
         else:
             # Default: ../skills relative to backend directory