Add a first-class `kimi` provider and `kimi://` DSN scheme for Moonshot AI's
OpenAI-compatible Chat Completions API. Both reuse provider/openai (no new
client, mirroring llama-swap's chat path). Default endpoint is the
international host; the China endpoint is reachable via a kimi:// LLM_* DSN.
- Credential is KIMI_API_KEY, read through the registry's injected envLookup
so it stays hermetically testable. WithAPIKey is passed unconditionally so
an unset KIMI_API_KEY can never fall through to the openai client's
OPENAI_API_KEY default.
- New openai.WithAPIKeyName option customizes the missing-key error hint
(default OPENAI_API_KEY); kimi names KIMI_API_KEY.
- Hermetic tests: built-in base URL + bearer, missing-key hint names
KIMI_API_KEY with no OPENAI fallthrough and no network hit, kimi:// scheme
round-trips against the China host.
- Docs in sync: README built-in table + DSN scheme list + support matrix,
.env.example, env.go DSN doc, ADR-0026 (+ index, backfilling 0024/0025),
progress.md.
Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>