* Release PK (v0.51.450): preserve custom provider namespace prefixes in model normalization (#4278)
Token-boundary check in _normalize_provider_id (exact token or prefix
followed strictly by ':' or '/'); explicit aliases for hyphenated
first-party names (google-gemini, google-ai-studio, claude-code); bare-prefix
family detection no longer fires on namespaced model IDs.
Closes#4278. Supersedes #4280 (rodboev) whose '-' boundary re-collapsed
claude-relay->anthropic.
Co-authored-by: b3nw
* gate fix (Codex CORE): add openai-api to _PROVIDER_ALIASES so the :/ token boundary doesn't drop the registered openai-api provider id to '' (would silently repair OpenAI API sessions to the profile default) + 2 regression tests
* gate fix (Opus): gate the streaming send-path bare-prefix loop on '/' not in model so custom namespaces (gemini_cli/, gpt_proxy/, claude-relay/) survive the send path — same #4278 collision Opus found in _apply_profile_provider_context_to_streaming_model; + regression test + CHANGELOG
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Co-authored-by: nesquena-hermes <agent@nesquena-hermes>
