Types

[marcopiraccini]

Adds TypeScript type declarations to @platformatic/leader. The package is JS-only, and consumers on TypeScript 6 hit TS7016: Could not find a declaration file for module '@platformatic/leader' (TS 6 tightened the implicit-any fallback that TS 5 used to allow). This was surfaced by the typescript-v6 bump in platformatic/platformatic-world#41; shipping types here unblocks it.

Changes:

• index.d.ts — export = createLeaderElector + declare namespace with Pool, Logger, NotificationChannel, LeaderElectorOptions, LeaderElector. Pool is a minimal structural type so the package's .d.ts doesn't pull in @types/pg or pino as peer-type requirements.
• package.json — "types": "index.d.ts", new test:types script (tsc -p tsconfig.json), typescript devDep.
• tsconfig.json — strict, noEmit, nodenext, scoped to index.d.ts + the smoke.
• test/types.test-d.ts — usage smoke (default-import, minimal + full options, returned methods). .test-d.ts suffix keeps it out of node --test test/*.test.js.
• .github/workflows/ci.yml — explicit Type check step in the lint job (npm run test:types); added Node 26 to the test matrix.

Verified locally: npm run test:types passes under both TypeScript 5.9 and 6.0; npm test on Node 22/24/26; running the workflow build in platformatic-world against TS 6 with the new types no longer errors.

[mcollina]

lgtm