feat: initialize rule generation tool

[camc314]

Add Rule Generator Tool

This PR adds a TypeScript-based rule generator tool to help create new type-aware ESLint rules for TSGolint. The tool:

• Downloads test files from typescript-eslint repository
• Parses test cases to extract valid/invalid examples
• Generates Go rule implementation stubs and test files
• Verifies that rules require type checking (since TSGolint focuses on type-aware rules)

The PR also:

• Adds a new new-rule command to the justfile for easy rule generation
• Adds TypeScript type checking for the rulegen tool in CI
• Includes necessary dependencies and configuration files

Example usage: just new-rule await-thenable

part of #250

[camc314]

• feat: initialize rule generation tool #252 👈 (View in Graphite)
• main

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[auvred]

This might be useful: I ported rule tests by patching @typescript-eslint/rule-tester. I never published this script because it's quite messy. AST-based conversion is unreliable, since some tests don't strictly follow the same AST shape. A better approach is to generate tests by introspecting the runtime values of the valid and invalid cases in JS RuleTester. A similar idea was used on the experimental-eslint-compat branch to convert ESLint core tests to Go: https://github.com/typescript-eslint/tsgolint/blob/009732a96109384fae40cc2cadc48c8f562b489b/tools/gen-eslint-core-rule-tests.ts

[camc314]

🤦 didn't even realize that script exists.