v2.0 — 31 C POC twins + harness fixes

- 31 C POC files, one per CVE folder: full seed construction + trigger +
  main(), self-contained, no app dependency. All compile clean with
  clang -O2 -Wall (zero warnings) on macOS arm64; each has a recorded
  oracle on this host.
- CMGetDMVersionLevelFromRPU ABI pinned by disassembly: macOS export is
  (CFDataRef), the Swift POC drives the 4-arg iOS surface — this is the
  mechanism behind the cm.rpu death oracle on the simulator build.
- Harness fixes: glyphCount guard, MachOInspector size guard, ModTools
  clamp, DeviceModel iPhone19,7, GPTPayload clamps, Gate patch display.
- POC comments rewritten English-only (31 swift + arc.rr + 5 py).
- README (en/zh): C twin column, .c anatomy section, compile/run
  examples, C oracle verification status.
- Dead if-let binding removed from Identity summary; v2.0 build 3.

CVE-2026-112646/CVE-2026-112646.c

@@ -0,0 +1,39 @@
+// sb.stash · SpringBoard · SBHomeScreenService stashed layout · CVE-2026-112646
+// Stashed layout name validation probe
+// C twin of the Swift POC: looks up SBHomeScreenService in this process, checks for
+// the 27.2 validation selector, and stats the container's IconState.plist.
+// Build: clang -O2 -o cve-2026-112646 CVE-2026-112646.c -lobjc
+// Run:   ./cve-2026-112646
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <objc/runtime.h>
+
+int main(void) {
+    // class lookup: SpringBoard's own classes are only registered inside SpringBoard
+    Class cls = objc_getClass("SBHomeScreenService");
+    printf("SBHomeScreenService in this process: %s\n", cls ? "yes" : "no");
+
+    SEL validator = sel_registerName("_validationErrorForStashedLayoutName:");
+    if (cls && class_respondsToSelector(cls, validator)) {
+        printf("  validation method present (27.2 fixed)\n");
+    } else {
+        printf("  validation method absent (27.0 unfixed)\n");
+    }
+
+    // container probe: IconState.plist only exists inside SpringBoard's container
+    const char *home = getenv("HOME");
+    char path[1024];
+    snprintf(path, sizeof path, "%s/Library/SpringBoard/IconState.plist", home ? home : "/tmp");
+    struct stat st;
+    if (stat(path, &st) == 0) {
+        printf("IconState.plist in this container: present (%lld B)\n", (long long)st.st_size);
+    } else {
+        printf("IconState.plist in this container: absent\n");
+    }
+    printf("CVE-2026-112646 · stashed-layout surface is SpringBoard-only; other processes\n"
+           "reach it only through the XPC surface the 27.0 build left unvalidated\n");
+    return 0;
+}