[PoC] Explore dedicated linting for AI

[zth]

Heavy WIP/POC and vibe coded, in an attempt to discover interesting and useful things we can do to help AI, at various levels and in various levels of "aggressiveness".

Add AI-oriented rescript-tools commands

Commands

• lint: Runs configurable AI-oriented lint checks on a file or project root using source and typed information.
• rewrite: Rewrites source into a narrower agent-oriented normal form, with optional diff output.
• active-rules: Lists lint and rewrite rules, whether they are active, and how they are configured.
• show: Returns hover-style semantic information for a symbol path.
• find-references: Finds references from either a symbol path or a source location.

Initial rules

• Lint:
  • forbidden-reference: Bans using configured module, value, and type references.
  • single-use-function: Reports local helper functions that are defined once and only used once.
  • alias-avoidance: Reports local aliases like let f = Module.f, type t = Module.t, and module M = Long.Path. Prefer the fully qualified reference instead.
  • forbidden-source-root-reference: Reports value and type references whose declarations come from configured source roots such as generated code folders.
  • preferred-type-syntax: Reports non-canonical type spellings like Dict.t<_> in favor of builtin syntax like dict<_>.
• Rewrite:
  • prefer-switch: Rewrites eligible if / else if chains and ternaries into canonical switch forms.
  • no-optional-some: Rewrites redundant ~label=?Some(expr) optional-argument wrapping into the direct labeled form.
  • preferred-type-syntax: Rewrites supported non-canonical type spellings like Dict.t<_> into builtin syntax like dict<_>.

Support

• Add .rescript-lint.json config support, a shipped JSON schema, AI tooling docs, and golden tests for the new command surface