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/ffi_objc.zig

@@ -105,7 +105,7 @@ pub const ObjcLowering = struct {
     ///   C=u8    S=u16   I=u32      Q=u64  f=f32  d=f64
     ///   @=id    #=Class :=SEL      *=C string  ^v=void* / generic ptr
     ///
-    /// Foreign-class pointers (`*UIView` etc.) encode as `@` (object
+    /// Runtime-class pointers (`*UIView` etc.) encode as `@` (object
     /// pointer). Other pointers fall to `^v` — the encoding is metadata,
     /// not ABI, so being conservative here is safe. Pass-by-value
     /// structs encode as `{Name=field0field1...}`; nested structs
@@ -260,7 +260,7 @@ pub const ObjcLowering = struct {
     /// `self.field` access work in A.2/A.3. Field-by-name resolution
     /// stays correct across the future repositioning.
     ///
-    /// Foreign-class members other than `.field` are ignored here —
+    /// Runtime-class members other than `.field` are ignored here —
     /// methods / `#extends` / `#implements` don't contribute to the
     /// state layout.
     pub fn objcDefinedStateStructType(self: ObjcLowering, fcd: *const ast.RuntimeClassDecl) TypeId {