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/c_import.zig

@@ -245,7 +245,7 @@ pub fn processCImport(
                     .name = pname,
                     .name_span = .{ .start = 0, .end = 0 },
                     .type_expr = ptype_node,
-                    // Foreign C param names (`i1`, `i2`, …) are RAW — exempt from
+                    // Extern C param names (`i1`, `i2`, …) are RAW — exempt from
                     // the reserved-type-name binding check; generated bindings
                     // must import without hand-edits.
                     .is_raw = true,