refactor(provider): support coding harnesses only

[steipete]

Summary

• define Clawpatch's provider boundary in a new root VISION.md
• support coding harnesses and agent CLIs only; direct model inference APIs are explicitly out of scope
• remove the MiniMax HTTP provider, its tests, current docs, and the undici runtime dependency
• reject removed and proposed direct-provider names through the normal unsupported-provider path
• align README, provider/spec docs, website copy, package contents, and changelog

Runtime proof

Built CLI on this branch:

clawpatch doctor --provider codex
providerVersion: codex-cli 0.139.0

clawpatch doctor --provider minimax
exit 2: unsupported provider: minimax

clawpatch doctor --provider deepseek
exit 2: unsupported provider: deepseek

Validation

• pnpm lint
• pnpm format:check
• pnpm test (824 passed, 1 skipped)
• pnpm build
• pnpm pack:smoke
• pnpm website:smoke
• final Codex autoreview: no actionable findings

[clawsweeper]

ClawSweeper status: review started.

I am starting a fresh review of this pull request: refactor(provider): support coding harnesses only This is item 1/1 in the current shard. Shard 0/1.

This placeholder means the worker is alive and reading the current context. I will edit this same comment with the actual review when the claws are done clicking.

Crustacean status: shell secured, claws on keyboard, evidence pebbles being sorted.