fix: sweep remaining provider-URL substring checks across codebase

Completes the hostname-hardening sweep — every substring check against a
provider host in live-routing code is now hostname-based. This closes the
same false-positive class for OpenRouter, GitHub Copilot, Kimi, Qwen,
ChatGPT/Codex, Bedrock, GitHub Models, Vercel AI Gateway, Nous, Z.AI,
Moonshot, Arcee, and MiniMax that the original PR closed for OpenAI, xAI,
and Anthropic.

New helper:
- utils.base_url_host_matches(base_url, domain) — safe counterpart to
  'domain in base_url'. Accepts hostname equality and subdomain matches;
  rejects path segments, host suffixes, and prefix collisions.

Call sites converted (real-code only; tests, optional-skills, red-teaming
scripts untouched):

run_agent.py (10 sites):
- AIAgent.__init__ Bedrock branch, ChatGPT/Codex branch (also path check)
- header cascade for openrouter / copilot / kimi / qwen / chatgpt
- interleaved-thinking trigger (openrouter + claude)
- _is_openrouter_url(), _is_qwen_portal()
- is_native_anthropic check
- github-models-vs-copilot detection (3 sites)
- reasoning-capable route gate (nousresearch, vercel, github)
- codex-backend detection in API kwargs build
- fallback api_mode Bedrock detection

agent/auxiliary_client.py (7 sites):
- extra-headers cascades in 4 distinct client-construction paths
  (resolve custom, resolve auto, OpenRouter-fallback-to-custom,
  _async_client_from_sync, resolve_provider_client explicit-custom,
  resolve_auto_with_codex)
- _is_openrouter_client() base_url sniff

agent/usage_pricing.py:
- resolve_billing_route openrouter branch

agent/model_metadata.py:
- _is_openrouter_base_url(), Bedrock context-length lookup

hermes_cli/providers.py:
- determine_api_mode Bedrock heuristic

hermes_cli/runtime_provider.py:
- _is_openrouter_url flag for API-key preference (issues #420, #560)

hermes_cli/doctor.py:
- Kimi User-Agent header for /models probes

tools/delegate_tool.py:
- subagent Codex endpoint detection

trajectory_compressor.py:
- _detect_provider() cascade (8 providers: openrouter, nous, codex, zai,
  kimi-coding, arcee, minimax-cn, minimax)

cli.py, gateway/run.py:
- /model-switch cache-enabled hint (openrouter + claude)

Bedrock detection tightened from 'bedrock-runtime in url' to
'hostname starts with bedrock-runtime. AND host is under amazonaws.com'.
ChatGPT/Codex detection tightened from 'chatgpt.com/backend-api/codex in
url' to 'hostname is chatgpt.com AND path contains /backend-api/codex'.

Tests:
- tests/test_base_url_hostname.py extended with a base_url_host_matches
  suite (exact match, subdomain, path-segment rejection, host-suffix
  rejection, host-prefix rejection, empty-input, case-insensitivity,
  trailing dot).

Validation: 651 targeted tests pass (runtime_provider, minimax, bedrock,
gemini, auxiliary, codex_cloudflare, usage_pricing, compressor_fallback,
fallback_model, openai_client_lifecycle, provider_parity, cli_provider_resolution,
delegate, credential_pool, context_compressor, plus the 4 hostname test
modules). 26-assertion E2E call-site verification across 6 modules passes.

agent/model_metadata.py

@@ -14,7 +14,7 @@ from urllib.parse import urlparse
 import requests
 import yaml
 
-from utils import base_url_hostname
+from utils import base_url_host_matches, base_url_hostname
 
 from hermes_constants import OPENROUTER_MODELS_URL
 
@@ -220,7 +220,7 @@ def _auth_headers(api_key: str = "") -> Dict[str, str]:
 
 
 def _is_openrouter_base_url(base_url: str) -> bool:
-    return "openrouter.ai" in _normalize_base_url(base_url).lower()
+    return base_url_host_matches(base_url, "openrouter.ai")
 
 
 def _is_custom_endpoint(base_url: str) -> bool:
@@ -1089,7 +1089,11 @@ def get_model_context_length(
     # 4b. AWS Bedrock — use static context length table.
     # Bedrock's ListFoundationModels doesn't expose context window sizes,
     # so we maintain a curated table in bedrock_adapter.py.
-    if provider == "bedrock" or (base_url and "bedrock-runtime" in base_url):
+    if provider == "bedrock" or (
+        base_url
+        and base_url_hostname(base_url).startswith("bedrock-runtime.")
+        and base_url_host_matches(base_url, "amazonaws.com")
+    ):
         try:
             from agent.bedrock_adapter import get_bedrock_context_length
             return get_bedrock_context_length(model)