Migrate scripts/ from JavaScript to TypeScript

[blackwood]

🎟️ Tracking

PM-35418

📔 Objective

Convert the build/validate/lint tooling under scripts/ from .mjs to .mts, type-checked with TypeScript via tsc --noEmit and run directly by Node's native type-stripping (no compile/emit step; Node >=22.18 strips types at runtime, already pinned via .nvmrc).

• Add tsconfig.json (strict, noEmit, NodeNext, verbatimModuleSyntax) and a typecheck script wired into npm run check; add typescript + @types/node.
• Add scripts/lib/types.mts with shared Location/Finding/LintResult/Form/ FormMapData shapes.
• Type the selector linter against css-what's own token types, using explicit type-predicate filters and in guards for the discriminated union.
• ajv/ajv-formats are CommonJS; alias their .default since NodeNext types the ESM default import as the module namespace.
• Repoint package.json scripts and lint-staged, and the README link, to .mts.

No behavior change: the built dist/forms.v1.json is byte-identical to the pre-migration output, and all 189 tests pass.

[github-actions]

🤖 Bitwarden Claude Code Review

Overall Assessment: APPROVE

This PR migrates the scripts/ build, validate, and lint tooling from .mjs to .mts, adds a strict tsconfig.json with tsc --noEmit type checking wired into npm run check, and introduces shared types in scripts/lib/types.mts. The migration is consistent end-to-end: all package.json scripts, lint-staged entries, and the README link are repointed to .mts, and CI invokes the unchanged npm run check / npm run build targets. The two logic-touching edits — destructuring in isIdOnly and the type-narrowing filter in findNamespacedTokens — preserve the original behavior.

Code Review Details

• ⚠️ : New dev dependency typescript (^6.0.3) added without an AppSec approval signal. Bitwarden's Dependency Review and Approval process requires AppSec review before introducing any new dependency, including dev/test. The PR references PM-35418 (a PM task), not a VULN task, and does not mention AppSec approval. The submitter should reach out to the AppSec team to initiate the dependency review process.
  • package.json:60

Dependency Changes

Package	Change	Ecosystem
typescript	New (^6.0.3)	npm
@types/node	22.19.17 → 22.20.0	npm