feat(models): remote model catalog manifest for OpenRouter + Nous Portal (#16033)

OpenRouter and Nous Portal curated picker lists now resolve via a JSON
manifest served by the docs site, falling back to the in-repo snapshot
when unreachable. Lets us update model lists without shipping a release.

Live URL: https://hermes-agent.nousresearch.com/docs/api/model-catalog.json
(source at website/static/api/model-catalog.json; auto-deploys via the
existing deploy-site.yml GitHub Pages pipeline on every merge to main).

Schema (v1) carries id + optional description + free-form metadata at
manifest, provider, and model levels. Pricing and context length stay
live-fetched via existing machinery (/v1/models endpoints, models.dev).

Config (new model_catalog section, default enabled):
  model_catalog.url       master manifest URL
  model_catalog.ttl_hours disk cache TTL (default 24h)
  model_catalog.providers.<name>.url   optional per-provider override

Fetch pipeline: in-process cache -> disk cache (fresh < TTL) -> HTTP
fetch -> disk-cache-on-failure fallback -> in-repo snapshot as last
resort. Never raises to callers; at worst returns the bundled list.

Changes:
- website/static/api/model-catalog.json    initial manifest (35 OR + 31 Nous)
- scripts/build_model_catalog.py           regenerator from in-repo lists
- hermes_cli/model_catalog.py              fetch + validate + cache module
- hermes_cli/models.py                     fetch_openrouter_models() +
                                           new get_curated_nous_model_ids()
- hermes_cli/main.py, hermes_cli/auth.py   Nous flows use the helper
- hermes_cli/config.py                     model_catalog defaults
- website/docs/reference/model-catalog.md  + sidebars.ts
- tests/hermes_cli/test_model_catalog.py   21 tests (validation, fetch
                                           success/failure, accessors,
                                           disabled, overrides, integration)

hermes_cli/config.py

@@ -959,6 +959,27 @@ DEFAULT_CONFIG = {
         "backup_count": 3,     # Number of rotated backup files to keep
     },
 
+    # Remotely-hosted model catalog manifest.  When enabled, the CLI fetches
+    # curated model lists for OpenRouter and Nous Portal from this URL,
+    # falling back to the in-repo snapshot on network failure.  Lets us
+    # update model picker lists without shipping a hermes-agent release.
+    # The default URL is served by the docs site GitHub Pages deploy.
+    "model_catalog": {
+        "enabled": True,
+        "url": "https://hermes-agent.nousresearch.com/docs/api/model-catalog.json",
+        # Disk cache TTL in hours.  Beyond this, the CLI refetches on the
+        # next /model or `hermes model` invocation; network failures
+        # silently fall back to the stale cache.
+        "ttl_hours": 24,
+        # Optional per-provider override URLs for third parties that want
+        # to self-host their own curation list using the same schema.
+        # Example:
+        #   providers:
+        #     openrouter:
+        #       url: https://example.com/my-curation.json
+        "providers": {},
+    },
+
     # Network settings — workarounds for connectivity issues.
     "network": {
         # Force IPv4 connections.  On servers with broken or unreachable IPv6,