refactor(ffi-linkage): Phase 9.3 — purge remaining 'foreign' from library/docs/example comments

Capital-Foreign + stale-identifier comment refs: library (Foreign Java types→Runtime,
foreign-class→runtime-class, foreign_class_map→runtime_class_map); docs/debugger
(foreign call→extern call); docs/fork-c ledger (foreign_class_map, protocol/foreign→
runtime-class); docs/inline-asm-design Deviation-6 obsolete #foreign-vs-extern design
RESOLVED to the landed extern/export reality; example comments (parseForeignClassDecl→
parseRuntimeClassDecl, checkForeignRefs→checkExternRefs, Foreign decls→Extern). Docs/
comments only — no build impact.

library/modules/ffi/objc.sx

@@ -10,7 +10,7 @@
 // ─── Obj-C primitive type aliases ───────────────────────────────────────
 // Named stand-ins for the three opaque Obj-C runtime types. They all
 // resolve to `*void` at the LLVM layer (no runtime cost) but improve
-// readability in foreign-class declarations and call sites.
+// readability in runtime-class declarations and call sites.
 //
 //   id    — any Obj-C instance pointer
 //   Class — a class object pointer
@@ -80,7 +80,7 @@ NSLog :: (fmt: *NSString) extern;
 // `defer view.release();` and `view.retain()` directly instead of going
 // through `objc_msgSend` casts. M2.3's `#extends`-aware dispatch finds
 // these methods automatically once a class roots its `#extends` chain at
-// NSObject (foreign classes in uikit.sx etc. add `#extends NSObject;` to
+// NSObject (runtime classes in uikit.sx etc. add `#extends NSObject;` to
 // inherit the surface).
 //
 // `release` is NOT a reserved keyword in sx — modern clang ARC bans