feat(python-scope): for-loop call-iterable typeBinding

Adds `(for_statement left: (identifier) right: (call function:
(identifier)))` to the typeBinding capture set. Combined with Unit 3's
return-type capture and the cross-file return-type propagation pass,
this makes `for u in get_users(): u.save()` resolve to `User.save`
even when `get_users` is imported from another module.

Captured as `@type-binding.alias` (rawName = function identifier,
without parens) so the existing chain-follow walks the alias to the
function's return-type binding without any new code path.

Verification:
- Flag-off: 191/191 (identical baseline).
- Flag-on: 12 fail / 179 pass (was 16/175; +4 for-loop call-iterable
  tests across get_users / get_repos fixtures).
- tsc --noEmit clean.

gitnexus/src/core/ingestion/languages/python/query.ts

@@ -108,6 +108,17 @@ export const PYTHON_SCOPE_QUERY = `
   left: (identifier) @type-binding.name
   right: (identifier) @type-binding.type) @type-binding.alias
 
+;; For-loop iterable of a free-call result:
+;;   def get_users() -> list[User]: ...
+;;   for u in get_users():   # u: get_users → User via chain follow
+;;       u.save()
+;; Captures the call's function identifier as the rawName. With
+;; \`propagateImportedReturnTypes\`, this works cross-file too.
+(for_statement
+  left: (identifier) @type-binding.name
+  right: (call
+    function: (identifier) @type-binding.type)) @type-binding.alias
+
 ;; Type bindings (variable annotations: \`u: User\` / \`u: User = x\`)
 (assignment
   left: (identifier) @type-binding.name

gitnexus/src/core/ingestion/languages/python/scopes.scm

@@ -125,6 +125,15 @@
   left: (identifier) @type-binding.name
   type: (type) @type-binding.type) @type-binding.annotation
 
+; For-loop iterable of a free-call result: `for u in get_users()` —
+; binds `u → get_users` so the chain post-pass follows it through
+; `get_users`'s return-type annotation (cross-file via
+; `propagateImportedReturnTypes`).
+(for_statement
+  left: (identifier) @type-binding.name
+  right: (call
+    function: (identifier) @type-binding.type)) @type-binding.alias
+
 ; ─── Type bindings: function return-type annotations ─────────────────────
 ;
 ; `def get_user() -> User:` — binds the function's NAME to its return