Add Kimi Code provider and OpenClaw 2026.4.12 compatibility

[EthanCai330]

Summary

This PR adds a separate built-in Kimi Code provider and fixes a startup crash after upgrading openclaw to 2026.4.12.

Changes

• add a new built-in provider: kimi-code
• keep existing moonshot behavior unchanged
• use https://api.kimi.com/coding as the default base URL
• use anthropic-messages as the protocol for Kimi Code
• use KIMI_CODE_API_KEY as the env var
• reuse the existing Moonshot icon
• update provider registry/types on both frontend and shared backend
• add unit tests for provider metadata and provider model sync
• add Electron E2E coverage for Kimi Code in provider lifecycle flow
• update README.md, README.zh-CN.md, and README.ja-JP.md

OpenClaw compatibility fix

After upgrading openclaw, InvestClaw hit this startup error in the Electron main process:

Error [ERR_PACKAGE_PATH_NOT_EXPORTED]: Package subpath './plugin-sdk/discord' is not defined by "exports"

This PR fixes that by making the old channel-specific openclaw/plugin-sdk/* imports optional and falling back to compatibility stubs when those exports are no longer available in newer OpenClaw releases.

This keeps the app from crashing on startup with openclaw@2026.4.12

Notes

• Moonshot (CN) still uses the original China endpoint and existing Kimi web search handling
• Kimi Code is intentionally separate and does not reuse the Moonshot-specific web search sync logic
• The channel target picker compatibility fix is designed to prevent startup failure first; newer OpenClaw extension APIs can be integrated later if needed

Validation

Ran successfully:

pnpm typecheck
pnpm test tests/unit/providers.test.ts tests/unit/provider-model-sync.test.ts
pnpm test tests/unit/channel-routes.test.ts
pnpm exec playwright test tests/e2e/provider-lifecycle.spec.ts
pnpm run build:vite