[SaladDay]

Change

Preserve the system role for thinking-enabled custom OpenAI-compatible connections to Kimi Coding (api.kimi.com and api.kimi.ai). Keep thinking, explicit compatibility overrides, other request options, and other providers unchanged.

This PR contains only the Kimi fix. DashScope is being submitted separately. Authentication, thinking-toggle behavior, and connection-test redesign are outside scope.

Validation

• The two endpoint regressions failed before the fix; the focused resolver suite passed all 62 tests.
• All 14 full-profile verification gates passed on macOS arm64 / Node 26.7.0 at 77ca68e. Current HEAD e0193bd has an identical file tree after reverting the DashScope addition.
• The original Kimi-only independent blind review found no actionable issues.

Publication and maintainer handoff

• Existing licenses and notices are preserved.
• No credentials, account data, private history, or user content is included.
• No source files were added or removed; tests extend an already registered file.
• Documentation impact is limited to the vendored patch ledger.
• Shared-source port: pending.