feat(ts): ts/unused-import rule — whole-statement delete of dead TS/JS imports

- binds names via tree-sitter (default, namespace, named + alias, type-only),
  keeps a statement when ANY bound name occurs outside it (word scan over
  comments/strings included): under-delete is the safe direction, mirroring
  the Java rule's asymmetry
- ESM caveat encoded in the policy: mixed live/dead statements are not
  touched — removing a specifier would still drop the module's side effects
- side-effect imports and 'export .. from' re-exports are never candidates
- parser/ts became a folder (mod/extract/unused_imports) to keep the
  4-entries-per-module rule; word_occurs shared via crate::parser
- java/rules/unused_imports now reuses the shared word scanner (DRY)

docs/SKILL.md

@@ -53,7 +53,11 @@ exit codes). Current Java rules: `java/unused-import` (deletes single-type
 imports whose name is provably unreferenced), `java/missing-import`
 (inserts the import of a project class used by simple name — unique FQN
 candidate required) and `java/import-order` (Google style: statics first,
-then single-type, ASCII-sorted, duplicates dropped). Unknown `--rule`
+then single-type, ASCII-sorted, duplicates dropped). TS/JS:
+`ts/unused-import` deletes whole statements whose every bound name is
+unreferenced; mixed statements (one name live) stay untouched because ESM
+imports carry module side effects, so partial specifier surgery is
+deliberately off. Unknown `--rule`
 fails with `INVALID_ARGUMENT` and lists the known ids. A candidate the
 engine cannot prove safe is reported with `"applied": false` and a
 `candidates` array of FQN options — resolve it yourself (pick one, add