fix(providers): complete NVIDIA NIM parity with other providers

Follow-up on the native NVIDIA NIM provider salvage. The original PR wired
PROVIDER_REGISTRY + HERMES_OVERLAYS correctly but missed several touchpoints
required for full parity with other OpenAI-compatible providers (xai,
huggingface, deepseek, zai).

Gaps closed:

- hermes_cli/main.py:
  - Add 'nvidia' to the _model_flow_api_key_provider dispatch tuple so
    selecting 'NVIDIA NIM' in `hermes model` actually runs the api-key
    provider flow (previously fell through silently).
  - Add 'nvidia' to `hermes chat --provider` argparse choices so the
    documented test command (`hermes chat --provider nvidia --model ...`)
    parses successfully.

- hermes_cli/config.py: Register NVIDIA_API_KEY and NVIDIA_BASE_URL in
  OPTIONAL_ENV_VARS so setup wizard can prompt for them and they're
  auto-added to the subprocess env blocklist.

- hermes_cli/doctor.py: Add NVIDIA NIM row to `_apikey_providers` so
  `hermes doctor` probes https://integrate.api.nvidia.com/v1/models.

- hermes_cli/dump.py: Add NVIDIA_API_KEY → 'nvidia' mapping for
  `hermes dump` credential masking.

- tests/tools/test_local_env_blocklist.py: Extend registry_vars fixture
  with NVIDIA_API_KEY to verify it's blocked from leaking into subprocesses.

- agent/model_metadata.py: Add 'nemotron' → 131072 context-length entry
  so all Nemotron variants get 128K context via substring match (rather
  than falling back to MINIMUM_CONTEXT_LENGTH).

- hermes_cli/models.py: Fix hallucinated model ID
  'nvidia/nemotron-3-nano-8b-a4b' → 'nvidia/nemotron-3-nano-30b-a3b'
  (verified against live integrate.api.nvidia.com/v1/models catalog).
  Expand curated list from 5 to 9 agentic models mapping to OpenRouter
  defaults per provider-guide convention: add qwen3.5-397b-a17b,
  deepseek-v3.2, llama-3.3-nemotron-super-49b-v1.5, gpt-oss-120b.

- cli-config.yaml.example: Document 'nvidia' provider option.

- scripts/release.py: Map asurla@nvidia.com → anniesurla in AUTHOR_MAP
  for CI attribution.

E2E verified: `hermes chat --provider nvidia ...` now reaches NVIDIA's
endpoint (returns 401 with bogus key instead of argparse error);
`hermes doctor` detects NVIDIA NIM when NVIDIA_API_KEY is set.

hermes_cli/main.py

@@ -1143,7 +1143,7 @@ def select_provider_and_model(args=None):
         _model_flow_kimi(config, current_model)
     elif selected_provider == "bedrock":
         _model_flow_bedrock(config, current_model)
-    elif selected_provider in ("gemini", "deepseek", "xai", "zai", "kimi-coding-cn", "minimax", "minimax-cn", "kilocode", "opencode-zen", "opencode-go", "ai-gateway", "alibaba", "huggingface", "xiaomi", "arcee", "ollama-cloud"):
+    elif selected_provider in ("gemini", "deepseek", "xai", "zai", "kimi-coding-cn", "minimax", "minimax-cn", "kilocode", "opencode-zen", "opencode-go", "ai-gateway", "alibaba", "huggingface", "xiaomi", "arcee", "nvidia", "ollama-cloud"):
         _model_flow_api_key_provider(config, selected_provider, current_model)
 
     # ── Post-switch cleanup: clear stale OPENAI_BASE_URL ──────────────
@@ -4954,7 +4954,7 @@ For more help on a command:
     )
     chat_parser.add_argument(
         "--provider",
-        choices=["auto", "openrouter", "nous", "openai-codex", "copilot-acp", "copilot", "anthropic", "gemini", "xai", "ollama-cloud", "huggingface", "zai", "kimi-coding", "kimi-coding-cn", "minimax", "minimax-cn", "kilocode", "xiaomi", "arcee"],
+        choices=["auto", "openrouter", "nous", "openai-codex", "copilot-acp", "copilot", "anthropic", "gemini", "xai", "ollama-cloud", "huggingface", "zai", "kimi-coding", "kimi-coding-cn", "minimax", "minimax-cn", "kilocode", "xiaomi", "arcee", "nvidia"],
         default=None,
         help="Inference provider (default: auto)"
     )