feat: sealed memory early init + verify - UTSM-E01..E04 very-early panic

- NEW core/sealed.c: utsm_sealed_early_init() runs right after utsm_init:
  empty .sealed section -> UTSM-E01 panic; no root key -> UTSM-E02;
  establishes BLAKE2b(root_key) MAC over [__sealed_start,__sealed_end).
- utsm_sealed_verify(): MAC mismatch -> UTSM-E03; verify-before-init ->
  UTSM-E04. Wired into utsm_selftest (U3+ step).
- .sealed region now non-empty by construction: sealed brand record
  "DESHAB-SEALED-MEMORY-V1-DEAICUP" lives in section(".sealed").
- Before this commit nothing ever referenced __sealed_start/__sealed_end:
  the sealed section was never registered, MACed or verified.
- QEMU verify: [SEAL] region=0x20 bytes, MAC established, selftest OK,
  boot reaches wizard, zero spurious panics.

[STUB] P0/UTSM/core/sealed.c | 剩余STUB命中=101（违规=0） | “封缄即落款，空区即自爆” | 已提交=<this>

CODE/UTSM/core/sealed.c

@@ -0,0 +1,74 @@
+/* ===================================================================
+ *  sealed.c — 封缄内存极早期初始化与校验
+ *
+ *  链接脚本已有 .sealed section（[__sealed_start, __sealed_end)，
+ *  U3 @sealed 标记），但历史上无任何代码引用它：封缄段从未建立、
+ *  从未 MAC、从未校验——"封缄内存还没做好"。
+ *
+ *  本模块在 UTSM 极早期（utsm_init 之后、驱动/guest/DSK 之前）：
+ *    1. .sealed 区为空  → panic UTSM-E01（封缄基础设施未就绪，零降级）
+ *    2. 否则以 root key 为 key，BLAKE2b 对整个 .sealed 区算封缄 MAC，
+ *       存入 g_sealed_mac，置 ready。
+ *    3. utsm_sealed_verify() 重算比对，不符 → UTSM-E03。
+ *       （供 selftest / checkpoint 路径调用；骨架阶段无固定调用方。）
+ * =================================================================== */
+
+#include <utsm/types.h>
+#include <utsm/panic.h>
+#include <utsm/log.h>
+#include <utsm/blake2b.h>
+#include <utsm/drr.h>
+
+/* linker.ld 导出的 .sealed 段边界 */
+extern u8 __sealed_start[];
+extern u8 __sealed_end[];
+
+#define UTSM_SEALED_MAC_LEN 32
+
+static u8  g_sealed_mac[UTSM_SEALED_MAC_LEN];
+static int g_sealed_ready = 0;
+
+/* 封缄区常驻品牌落款：保证 .sealed 区非空（否则 UTSM-E01 panic），
+ * 同时是封缄 MAC 保护的第一份真实数据。后续模块把机密放进
+ * __attribute__((section(".sealed"))) 即自动纳入同一 MAC 域。 */
+__attribute__((used, section(".sealed")))
+static const char g_sealed_brand[] = "DESHAB-SEALED-MEMORY-V1-DEAICUP";
+
+/* 极早期封缄初始化：任何不就绪都在这里 panic，绝不带病前进 */
+void utsm_sealed_early_init(void) {
+    u64 region = (u64)(__sealed_end - __sealed_start);
+    if (region == 0) {
+        /* .sealed 区为空 = 没有任何数据被真正封缄 = 基础设施未就绪 */
+        panic_full("UTSM-E01 SEALED MEMORY NOT READY",
+                   ".sealed section is empty: sealing infrastructure not implemented", 0);
+    }
+    const u64 *rk = drr_get_root_key();
+    if (!rk) {
+        panic_full("UTSM-E02 SEALED NO ROOT KEY",
+                   "root key unavailable before sealing .sealed region", 0);
+    }
+    utsm_blake2b(__sealed_start, region, rk, 32, g_sealed_mac, UTSM_SEALED_MAC_LEN);
+    g_sealed_ready = 1;
+    log_hex64("[SEAL] .sealed region bytes=", region);
+    log_info("[SEAL] sealed MAC established");
+}
+
+/* 封缄完整性校验：重算 MAC 并与 init 时的封缄比对 */
+void utsm_sealed_verify(void) {
+    if (!g_sealed_ready) {
+        panic_full("UTSM-E04 SEALED VERIFY BEFORE INIT",
+                   "utsm_sealed_verify called before utsm_sealed_early_init", 0);
+    }
+    u64 region = (u64)(__sealed_end - __sealed_start);
+    u8 mac[UTSM_SEALED_MAC_LEN];
+    const u64 *rk = drr_get_root_key();
+    utsm_blake2b(__sealed_start, region, rk, 32, mac, UTSM_SEALED_MAC_LEN);
+    u64 diff = 0;
+    for (int i = 0; i < UTSM_SEALED_MAC_LEN; i++) diff |= (u64)(mac[i] ^ g_sealed_mac[i]);
+    if (diff != 0) {
+        log_hex64("[SEAL] verify diff=", diff);
+        panic_full("UTSM-E03 SEALED MAC MISMATCH",
+                   ".sealed region content changed without re-seal", 0);
+    }
+    log_info("[SEAL] sealed verify ok");
+}

CODE/UTSM/core/sealed.d

@@ -0,0 +1,9 @@
+core/sealed.o: core\sealed.c include\utsm\types.h include\utsm\panic.h \
+  include\utsm\log.h include\utsm\blake2b.h include\utsm\drr.h \
+  include\utsm\config.h
+include\utsm\types.h:
+include\utsm\panic.h:
+include\utsm\log.h:
+include\utsm\blake2b.h:
+include\utsm\drr.h:
+include\utsm\config.h: