feat: re-instrument per STUB rules - all silent placeholders now panic

- PE-E03 pe_loader.c: unsupported base-reloc type silently skipped -> panic
- PE-E04 pe_shim.c ReadFile: fake TRUE+0-bytes ("pretend EOF") -> panic
- PE-E05 pe_shim.c CreateFileA: no file backend -> panic (no honest-failure excuse)
- PE-E06/E07 x86emu32.c: emu IAT unimplemented API / shim index OOB -> panic
- NETST-E01 net.c: netdev stats all-zero placeholder ("lying zero traffic") -> panic
- apic.c comment: SIPI reserved now points to DKM-E03 skeleton
- pe_dll_manager comments: circular-dep stub call now documented as PE-E01
- virtio_blk.c: capacity declaration marked as instrumentation whitelist
- QEMU verify: wizard -> Save -> verify ok -> login success -> desktop ready,
  zero spurious panics

[STUB] P1/UTSM/pe+net re-instrument sweep | 剩余STUB命中=101 (全部为 panic 坐标注释 /
IDT halt-stub 防御术语 / 白名单) | “未成之物，不留活口”

CODE/UTSM/pe/pe_dll_manager.c

@@ -356,7 +356,9 @@ int pe_dll_load(const char *dll_name, u64 *out_base) {
             return 0;
         }
         if (e->state == DLL_STATE_LOADING) {
-            /* 循环依赖：返回 -1，调用方填 unimpl stub */
+            /* 循环依赖：返回 -1，调用方填 unimpl stub——该 stub 被调用
+             * 即 PE-E01 莲花 panic（见 pe_shim.c shim_unimpl64），
+             * 不存在静默降级出口。 */
             if (out_base) *out_base = 0;
             return -1;
         }