fix(agent): register Upstage keys in the env-var catalog

`UPSTAGE_API_KEY` / `UPSTAGE_BASE_URL` were wired through the provider
resolver, auth registry, and the EnvPage grouping, but never added to
`OPTIONAL_ENV_VARS` in hermes_cli/config.py. The dashboard/desktop
Providers page builds its list from that catalog (`/api/env` iterates
`OPTIONAL_ENV_VARS`), so with no entry the keys were never emitted and
"Upstage Solar" never rendered — the EnvPage prefix group stayed empty.

Add both keys under `category: "provider"` (matching gmi/minimax) so they
show up in `hermes dashboard` / `hermes desktop` under "Upstage Solar".
Adds a regression test asserting the catalog contains them, mirroring the
existing GMI coverage.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

hermes_cli/config.py

@@ -3707,6 +3707,21 @@ OPTIONAL_ENV_VARS = {
         "category": "provider",
         "advanced": True,
     },
+    "UPSTAGE_API_KEY": {
+        "description": "Upstage API key for Solar LLM models",
+        "prompt": "Upstage API Key",
+        "url": "https://console.upstage.ai/api-keys",
+        "password": True,
+        "category": "provider",
+    },
+    "UPSTAGE_BASE_URL": {
+        "description": "Upstage base URL override (default: https://api.upstage.ai/v1)",
+        "prompt": "Upstage base URL (leave empty for default)",
+        "url": None,
+        "password": False,
+        "category": "provider",
+        "advanced": True,
+    },
     "AWS_REGION": {
         "description": "AWS region for Bedrock API calls (e.g. us-east-1, eu-central-1)",
         "prompt": "AWS Region",