feat(config): support explicit tsgo checker

[chrisolszewski]

Summary

Lets you choose tsgo, the native TypeScript preview compiler, as the TypeScript
checker. Defaults don't change: tsc stays the default, and tsgo runs only when
you ask for it.

What changed

• format.rs, configure.rs: treat tsgo the same way as tsc where the
  invocation is identical, plus Windows shim detection.
• Config and schema: add tsgo to the checker enum (opencode and pi), the schema
  asset, and the generator.
• Docs: README lists tsc as the default and tsgo as an explicit opt-in.
• Tests: checker selection in configure.

Why opt-in only

tsgo is still a preview build. Making it the default would change type-checking
for every TypeScript project, so it runs only when configured.

Validation

• cargo fmt --check; cargo test -p agent-file-tools configure
• bun run typecheck in both plugins

---

Summary by cubic

Adds opt-in support for tsgo as the TypeScript checker. Defaults remain tsc; nothing changes unless you explicitly configure tsgo.

• New Features

  • Added tsgo to checker enums and schemas across AFT, opencode and pi plugins.
  • Execute tsgo with the same args as tsc, with Windows shim detection, diagnostic parsing, and consistent checker_command handling (no behavior change).
  • Added install hint for tsgo and tests for selection, diagnostics, and configure warnings.

• Migration

  • Enable by setting "checker": { "typescript": "tsgo" } in your config.
  • Install @typescript/native-preview (dev or global).

^{Written for commit 9a96add. Summary will update on new commits. Review in cubic}

[cubic-dev-ai]

1 issue found across 9 files

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[cubic-dev-ai]

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