fix(azure-foundry): auto-route gpt-5.x / codex / o-series to Responses API (#16361)

Azure Foundry deploys GPT-5.x, codex-*, and o1/o3/o4 reasoning models as
Responses-API-only.  Calling /chat/completions against these deployments
returns 400 'The requested operation is unsupported.', which broke any
user who ran 'hermes model' on Azure, picked a gpt-5/codex deployment,
and kept the default api_mode: chat_completions.  Verified in a user
debug bundle on 2026-04-26: gpt-5.3-codex failed on synopsisse.openai.azure.com
with that exact payload while gpt-4o-pure on the same endpoint worked.

Adds azure_foundry_model_api_mode(model_name) that returns
codex_responses when the model name starts with gpt-5, codex, o1, o3,
or o4 — otherwise None so chat_completions / anthropic_messages stay
untouched for gpt-4o, Llama, Claude-via-Anthropic, etc.

Resolver (both the direct Azure Foundry path and the pool-entry path)
consults it and upgrades api_mode unless the user explicitly picked
anthropic_messages.  target_model (from /model mid-session switch)
takes precedence over the persisted default so switching from gpt-4o
to gpt-5.3-codex routes correctly before the next request.

Docs: correct the azure-foundry guide which previously claimed Azure
keeps gpt-5.x on chat completions — that was only true for early Azure
OpenAI, not Azure Foundry codex/o-series deployments.

Tests: 14 unit tests for azure_foundry_model_api_mode + 6 integration
tests in TestAzureFoundryResolution covering Bob's exact scenario,
target_model override, anthropic_messages guard, and o3-mini.

website/docs/guides/azure-foundry.md

@@ -72,7 +72,7 @@ model:
 
 Important behaviour:
 
-- **gpt-5.x stays on `/chat/completions`.** Unlike `api.openai.com`, Azure OpenAI does not support the Responses API — Hermes detects Azure endpoints and keeps gpt-5.x on `chat_completions` where Azure actually serves it.
+- **GPT-5.x, codex, and o-series auto-route to the Responses API.** Azure Foundry deploys GPT-5 / codex / o1 / o3 / o4 models as Responses-API-only — calling `/chat/completions` against them returns `400 "The requested operation is unsupported."`. Hermes detects these model families by name and upgrades `api_mode` to `codex_responses` transparently, even when `config.yaml` still reads `api_mode: chat_completions`. GPT-4, GPT-4o, Llama, Mistral, and other deployments stay on `/chat/completions`.
 - **`max_completion_tokens` is used automatically.** Azure OpenAI (like direct OpenAI) requires `max_completion_tokens` for gpt-4o, o-series, and gpt-5.x models. Hermes sends the right parameter based on the endpoint.
 - **Pre-v1 endpoints that require `api-version`.** If you have a legacy base URL like `https://<resource>.openai.azure.com/openai?api-version=2025-04-01-preview`, Hermes extracts the query string and forwards it via `default_query` on every request (the OpenAI SDK otherwise drops it when joining paths).