fix: auth review fixes — token revocation, WS auth, seeding, and hardening

Refresh/logout and token robustness
- drop the post-rotation refresh_tokens row delete in auth_refresh so
  logout blacklists the current (rotated) refresh token; remove the
  dead _clear_refresh_token_after_rotation helper and clear_active_refresh_token
- reject non-object JWT payloads in _extract_unverified_sub so crafted
  Authorization headers return 401 instead of crashing with 500

SQLite user store
- make builtin-admin seeding idempotent: on a concurrent first start the
  losing seeder re-checks, finds the winner, and returns instead of
  raising IntegrityError
- per-thread sqlite connections + busy_timeout so Flask worker threads
  don't hit cross-thread ProgrammingError / SQLITE_BUSY
- add LogsDirectory + /var/log/vacuum-wall to ReadWritePaths in both
  systemd units so the fallback admin password actually lands on disk

Frontend
- skip apiFetch 401-recovery for public auth endpoints so a failed
  login no longer logs out a valid session
- add /passkeys to the nav (passkey registration was unreachable);
  remove the dead checkWebAuthnCapable export
- drop the CSP-blocked inline WS-URL script and the
  __WS_URL_PLACEHOLDER__ plumbing; the WS URL is derived from location

Daemon / WS
- parse Sec-WebSocket-Protocol manually (web.Request.get_subprotocols
  does not exist in aiohttp 3.13); X-Auth-Token is a custom-nginx
  fallback only — docstring and security docs corrected

Install / system
- bootstrap_auth.py is now idempotent: preserves existing auth config
  and syncs the admin password on re-runs (new reset_password helper)
- WebUI server block renders auth_basic off (the UI is JWT-protected)
- install.sh chown/chmod skips .git to avoid git dubious-ownership
  breakage
- tolerate unreadable /etc/wireguard during system import

Contracts / docs
- create_user returns 409 on duplicate username per docs/api.md
- correct docs/api.md response shapes, docs/security.md blacklist
  cleanup wording + one-refresh-per-user caveat, stale WS-URL
  references, and the .htpasswd description

Tests: +7 regression tests (rotation/logout revocation, crafted-token
401, concurrent seeding); placeholder-substitution tests replaced with
serve-as-is SPA root tests.

lib/auth_users.py

@@ -207,6 +207,31 @@ def update_password(username: str, old_password: str, new_password: str) -> bool
     return True
 
 
+def reset_password(username: str, new_password: str) -> None:
+    """Force-reset a user's password without verifying the old one.
+
+    Non-interactive variant for install-time and lockout recovery: the
+    installer does not know the previous password by construction. Rotates
+    the user's JWT secret and blacklists the active refresh token,
+    invalidating all existing sessions.
+
+    Args:
+        username: The user to reset.
+        new_password: New plain-text password.
+
+    Raises:
+        ValueError: If the user does not exist.
+    """
+    if find_user(username) is None:
+        raise ValueError(f"User {username!r} not found")
+
+    blacklist_active_refresh_token(username)
+    new_hash = hash_password(new_password)
+    rotate_user_secret(username)
+    db = get_db()
+    db.run(Q_UPDATE_PASSWORD, (new_hash, username))
+
+
 def update_permissions(username: str, permissions: dict[str, str]) -> None:
     """Update a user's permissions and invalidate all existing tokens.