refactor(ffi-linkage): Phase 9.3 — purge 'foreign' from comments (src caps + examples + docs)

src/: ~21 capital-Foreign comments the case-sensitive verify grep missed
(Foreign-class→Runtime-class, Foreign path→Runtime path, Foreign decls→Extern decls,
FOREIGN function→extern function) across calls/inst/ffi_objc/jni_descriptor/emit_llvm/
c_import/lower.*/ops. src 'foreign' now = ONLY the hash_foreign token + 4 rejection
messages (9.0-delete targets). examples/*.sx comments → extern/runtime-class (1219
stdout regen; KEPT 1176). docs/inline-asm-design + debugger purged. Comments only —
no build impact. 9.0 ratified: DELETE hash_foreign token next.

src/ir/lower/call.zig

@@ -722,7 +722,7 @@ pub fn lowerCall(self: *Lowering, c_in: *const ast.Call) Ref {
                     switch (self.namespaceAliasVerdict(oname)) {
                         .target => |target| {
                             const fd = Lowering.namespaceFnMember(&target, fa.field) orelse break :gate;
-                            // Foreign / builtin / #compiler bodies keep their
+                            // Extern / builtin / #compiler bodies keep their
                             // literal global symbol — the existing bare-name
                             // machinery below resolves them.
                             switch (fd.body.data) {
@@ -891,7 +891,7 @@ pub fn lowerCall(self: *Lowering, c_in: *const ast.Call) Ref {
                 method_args.append(self.alloc, a) catch unreachable;
             }
 
-            // Foreign-class DSL: `inst.method(args)` where `inst`'s
+            // Runtime-class DSL: `inst.method(args)` where `inst`'s
             // type is an alias declared by `#jni_class("...") { ... }`
             // (or its parallel forms). Routes to the JNI dispatch
             // shape, descriptor derived from the sx signature.
@@ -2236,7 +2236,7 @@ pub fn resolveCallParamTypes(self: *Lowering, c: *const ast.Call, sel_author: ?*
             }
         }
         if (self.getStructTypeName(obj_ty)) |sname| {
-            // Foreign-class receiver (`#objc_class` / `#jni_class` / etc.):
+            // Runtime-class receiver (`#objc_class` / `#jni_class` / etc.):
             // resolve the method from `runtime_class_map` walking `#extends`.
             // Without this path, `target_type` for each arg falls back to
             // whatever `self.target_type` was on entry — typically the

src/ir/lower/decl.zig

@@ -1112,7 +1112,7 @@ pub fn registerTopLevelGlobal(self: *Lowering, vd: *const ast.VarDecl) void {
             d.addFmt(.err, null, "top-level var '{s}' has no type annotation and no initializer to infer from", .{vd.name});
         break :blk .void;
     };
-    // Foreign / extern globals reference a symbol defined in libSystem etc.
+    // Extern globals reference a symbol defined in libSystem etc.
     // (`_NSConcreteStackBlock : *void extern;` or `… : *void extern;`). The C
     // symbol name is the optional override (`extern_name`) or the sx name itself.
     const sym_name = vd.extern_name orelse vd.name;
@@ -2081,7 +2081,7 @@ pub fn declareFunction(self: *Lowering, fd: *const ast.FnDecl, name: []const u8)
         }
     }
 
-    // Foreign declarations with a trailing variadic param map to the C
+    // Extern declarations with a trailing variadic param map to the C
     // calling convention's `...` tail. Drop the variadic param from the
     // IR signature (it has no C-level slot) and set is_variadic.
     // Bare `extern` import: an external C symbol declared via the `extern`
@@ -2194,7 +2194,7 @@ pub fn registerQualifiedFn(self: *Lowering, ns_name: []const u8, fd: *const ast.
     // collision assert; registering a qualified alias for them
     // would divert that machinery and strand a per-call type binding.
     if (fd.type_params.len > 0 or hasComptimeParams(fd) or isPackFn(fd)) return;
-    // Foreign / builtin / #compiler bodies keep their literal name; a
+    // Extern / builtin / #compiler bodies keep their literal name; a
     // qualified alias has no distinct symbol to resolve to.
     switch (fd.body.data) {
         .builtin_expr, .compiler_expr => return,
@@ -2300,7 +2300,7 @@ pub fn lazyLowerFunction(self: *Lowering, name: []const u8) void {
     }
     // No AST? (builtins, extern functions, or imported functions not in this file)
     const fd = self.program_index.fn_ast_map.get(name) orelse return;
-    // Foreign declarations stay as extern stubs but need to be REGISTERED
+    // Extern declarations stay as extern stubs but need to be REGISTERED
     // in the current module so callers get a real FuncId. Without this,
     // a comptime-lowered function (e.g. `concat` from std.sx pulled into
     // a fresh ct_module via `evalComptimeString`) emits `.call` against a

src/ir/lower/ffi.zig

@@ -778,7 +778,7 @@ pub fn lowerSuperCall(
     } }, ret_ty);
 }
 
-// ── Foreign-class registration ──────────────────────────────────
+// ── Runtime-class registration ──────────────────────────────────
 
 /// Register a runtime-class declaration. The alias goes into
 /// `runtime_class_map` for method-dispatch lookup. The underlying

src/ir/lower/objc_class.zig

@@ -137,8 +137,8 @@ pub fn lookupObjcDefinedStateFieldOnPointer(self: *Lowering, obj_expr: *const as
     if (pointee_info != .@"struct") return null;
     const struct_name = self.module.types.getString(pointee_info.@"struct".name);
     const fcd = self.program_index.runtime_class_map.get(struct_name) orelse return null;
-    // Only sx-defined Obj-C classes have a state struct. Foreign
-    // classes' fields are purely declaration metadata (no state).
+    // Only sx-defined Obj-C classes have a state struct. Extern (referenced)
+    // runtime classes' fields are purely declaration metadata (no state).
     if (fcd.is_extern or fcd.runtime != .objc_class) return null;
     // Skip property fields — those dispatch via the M2.2 getter/setter
     // path. Plain instance fields take the ivar+gep path.