fix: restrict provider URL detection to exact hostname matches

[Aslaaen]

Summary

Fix provider URL auto-detection so direct OpenAI and xAI routing is based on the parsed URL hostname instead of substring matches.

Previously, custom endpoints such as:

• https://api.openai.com.example/v1
• https://proxy.example.test/api.openai.com/v1
• https://api.x.ai.example/v1

could be misclassified as native OpenAI/xAI endpoints because detection searched the whole URL string. That could incorrectly force codex_responses routing for OpenAI-compatible custom providers that only include those strings in their host suffix or path.

This change parses the base URL hostname and only treats exact api.openai.com and api.x.ai hosts as native direct endpoints.

Changes

• Add host parsing helper for provider URL detection.
• Update hermes_cli.runtime_provider._detect_api_mode_for_url() to use exact hostname checks.
• Cache the parsed base URL hostname on AIAgent.base_url.
• Update AIAgent direct OpenAI and xAI checks to use exact hostname matching.
• Add regression tests for host suffix and path-segment false positives.

Tests

• uv run --frozen --extra dev python -m pytest -q -n 4 tests/hermes_cli/test_detect_api_mode_for_url.py tests/agent/test_direct_provider_url_detection.py
• .venv\Scripts\python.exe -m py_compile hermes_cli\runtime_provider.py run_agent.py tests\hermes_cli\test_detect_api_mode_for_url.py tests\agent\test_direct_provider_url_detection.py
• git diff --check -- hermes_cli\runtime_provider.py run_agent.py tests\hermes_cli\test_detect_api_mode_for_url.py tests\agent\test_direct_provider_url_detection.py

[teknium1]

Merged via PR #13302 — your original commit was cherry-picked onto current main with your authorship preserved (see 5356797f on main). Thank you for the fix, @Aslaaen! Your report caught a real false-positive class, and we took it as the starting point for a full codebase sweep that hardened 26 more call sites across OpenRouter, GitHub Copilot, Kimi, Qwen, ChatGPT/Codex, Bedrock, GitHub Models, Vercel AI Gateway, Nous, Z.AI, Moonshot, Arcee, and MiniMax.