ios + ir cleanup

- ios: --target ios/ios-sim shorthands, iOS SDK auto-discovery,
  #framework directive + BuildOptions.add_framework hook,
  .app bundle + Info.plist + codesign (ad-hoc and real),
  --codesign-identity/--provisioning-profile/--entitlements flags,
  modules/std/{objc,uikit}.sx, dynamic class registration,
  typed objc_msgSend cast pattern, UIApplicationMain handoff,
  UIWindow scene attach. Runs on iPhone hardware.
- ir: silent .s64 defaults → loud diagnostics,
  resolveReturnType infers from body, sub-byte int sizes match LLVM,
  tuple type interning includes names, compile errors exit 1
- issue-NNNN convention: resolved bugs rename to focused features
- 50 regression tests passing

src/ast.zig

@@ -71,6 +71,7 @@ pub const Node = struct {
         compiler_expr: void,
         foreign_expr: ForeignExpr,
         library_decl: LibraryDecl,
+        framework_decl: FrameworkDecl,
         function_type_expr: FunctionTypeExpr,
         closure_type_expr: ClosureTypeExpr,
         tuple_type_expr: TupleTypeExpr,
@@ -448,6 +449,10 @@ pub const LibraryDecl = struct {
     name: []const u8, // sx-side constant name
 };
 
+pub const FrameworkDecl = struct {
+    name: []const u8, // framework name, e.g. "Foundation"
+};
+
 pub const FunctionTypeExpr = struct {
     param_types: []const *Node,
     param_names: ?[]const ?[]const u8 = null, // optional documentation names