Move public types to dedicated entry

[bcomnes]

Summary

• Add a dedicated root types.ts public type entry that emits types.d.ts for @domstack/static/types.js consumers.
• Remove duplicated public JSDoc typedef re-exports from index.js while keeping runtime exports typed via index.d.ts.
• Add an internal #types import alias for repo-local type references without relative path climbs.
• Update docs/examples/test fixtures to import public types from @domstack/static/types.js.
• Add a v12 migration stub documenting the type entry move.
• Replace the type export smoke test with a .ts test that exercises the exported types.

Validation

• npm run clean && npm run test:tsc && npm run build:declaration
• npm run build
• npm test

Notes:

• Cleaned generated declarations/public output after validation so the branch does not include generated artifacts.
• Kept "types": "./index.d.ts" for the runtime package entry; type-only imports now use @domstack/static/types.js.