* fix(cloudflare): route native Workers AI provider through OpenAI-compatible endpoint
* fix(cloudflare): guard missing account id and migrate legacy /ai/run base
Centralize the OpenAI-compatible api_base default in get_complete_url so it
is built in one place instead of being duplicated in main.py. When neither
api_base nor CLOUDFLARE_ACCOUNT_ID is set the call now fails fast with a clear
error rather than sending a request to a URL containing the literal 'None'.
An api_base still pinned to the legacy Workers AI '/ai/run' path is rewritten
to the '/ai/v1' OpenAI-compatible endpoint with a deprecation warning, so
users who hardcoded the previous default migrate gracefully instead of hitting
a silently broken '/ai/run/chat/completions' URL.
* fix(cloudflare): treat empty api_base as unset when resolving URL
* fix(cloudflare): treat empty CLOUDFLARE_ACCOUNT_ID as unset
An empty or whitespace-only CLOUDFLARE_ACCOUNT_ID slipped past the None
guard and built .../accounts//ai/v1, producing the same confusing 404 the
PR set out to prevent. Normalize the secret with normalize_nonempty_secret_str
so blank values raise the explicit missing-account-id error instead.
Newer Cloudflare Workers AI models (e.g. Nemotron) emit 'response_text'
instead of 'response' on streamed chunks. The non-streaming path was
already updated to fall back to 'response_text' (#26385), but the
streaming chunk parser still only read 'response', which caused
streaming requests against those models to silently produce empty
content.
Mirror the non-streaming fallback in CloudflareChatResponseIterator.chunk_parser
and add a streaming test for the response_text shape.
Co-authored-by: Mateo Wang <mateo-berri@users.noreply.github.com>
