security(runtime_provider): close OLLAMA_API_KEY substring-leak sweep miss (#13522)

Two call sites still used a raw substring check to identify ollama.com:

  hermes_cli/runtime_provider.py:496:
      _is_ollama_url = "ollama.com" in base_url.lower()

  run_agent.py:6127:
      if fb_base_url_hint and "ollama.com" in fb_base_url_hint.lower() ...

Same bug class as GHSA-xf8p-v2cg-h7h5 (OpenRouter substring leak), which
was fixed in commit dbb7e00e via base_url_host_matches() across the
codebase. The earlier sweep missed these two Ollama sites. Self-discovered
during April 2026 security-advisory triage; filed as GHSA-76xc-57q6-vm5m.

Impact is narrow — requires a user with OLLAMA_API_KEY configured AND a
custom base_url whose path or look-alike host contains 'ollama.com'.
Users on default provider flows are unaffected. Filed as a draft advisory
to use the private-fork flow; not CVE-worthy on its own.

Fix is mechanical: replace substring check with base_url_host_matches
at both sites. Same helper the rest of the codebase uses.

Tests: 67 -> 71 passing. 7 new host-matcher cases in
tests/test_base_url_hostname.py (path injection, lookalike host,
localtest.me subdomain, ollama.ai TLD confusion, localhost, genuine
ollama.com, api.ollama.com subdomain) + 4 call-site tests in
tests/hermes_cli/test_runtime_provider_resolution.py verifying
OLLAMA_API_KEY is selected only when base_url actually targets
ollama.com.

Fixes GHSA-76xc-57q6-vm5m

run_agent.py

@@ -6123,8 +6123,9 @@ class AIAgent:
             fb_base_url_hint = (fb.get("base_url") or "").strip() or None
             fb_api_key_hint = (fb.get("api_key") or "").strip() or None
             # For Ollama Cloud endpoints, pull OLLAMA_API_KEY from env
-            # when no explicit key is in the fallback config.
-            if fb_base_url_hint and "ollama.com" in fb_base_url_hint.lower() and not fb_api_key_hint:
+            # when no explicit key is in the fallback config. Host match
+            # (not substring) — see GHSA-76xc-57q6-vm5m.
+            if fb_base_url_hint and base_url_host_matches(fb_base_url_hint, "ollama.com") and not fb_api_key_hint:
                 fb_api_key_hint = os.getenv("OLLAMA_API_KEY") or None
             fb_client, _resolved_fb_model = resolve_provider_client(
                 fb_provider, model=fb_model, raw_codex=True,