fix(security): harden dashboard API against unauthenticated access (#9800)

Addresses responsible disclosure from FuzzMind Security Lab (CVE pending).

The web dashboard API server had 36 endpoints, of which only 5 checked
the session token. The token itself was served from an unauthenticated
GET /api/auth/session-token endpoint, rendering the protection circular.
When bound to 0.0.0.0 (--host flag), all API keys, config, and cron
management were accessible to any machine on the network.

Changes:
- Add auth middleware requiring session token on ALL /api/ routes except
  a small public whitelist (status, config/defaults, config/schema,
  model/info)
- Remove GET /api/auth/session-token endpoint entirely; inject the token
  into index.html via a <script> tag at serve time instead
- Replace all inline token comparisons (!=) with hmac.compare_digest()
  to prevent timing side-channel attacks
- Block non-localhost binding by default; require --insecure flag to
  override (with warning log)
- Update frontend fetchJSON() to send Authorization header on all
  requests using the injected window.__HERMES_SESSION_TOKEN__

Credit: Callum (@0xca1x) and @migraine-sudo at FuzzMind Security Lab

hermes_cli/main.py

@@ -4421,6 +4421,7 @@ def cmd_dashboard(args):
         host=args.host,
         port=args.port,
         open_browser=not args.no_open,
+        allow_public=getattr(args, "insecure", False),
     )
 
 
@@ -5932,6 +5933,10 @@ Examples:
     dashboard_parser.add_argument("--port", type=int, default=9119, help="Port (default 9119)")
     dashboard_parser.add_argument("--host", default="127.0.0.1", help="Host (default 127.0.0.1)")
     dashboard_parser.add_argument("--no-open", action="store_true", help="Don't open browser automatically")
+    dashboard_parser.add_argument(
+        "--insecure", action="store_true",
+        help="Allow binding to non-localhost (DANGEROUS: exposes API keys on the network)",
+    )
     dashboard_parser.set_defaults(func=cmd_dashboard)
 
     # =========================================================================