fix: 图片密钥内存扫描通过子进程调用解决 task_for_pid 权限问题

Electron 进程缺少 com.apple.security.cs.debugger entitlement，
导致 ScanMemoryForImageKey 中的 task_for_pid 调用失败（kr=5）。

新增 image_scan_helper 子进程包装程序（与 xkey_helper 方案一致）：
- 新建 resources/image_scan_helper.c：dlopen libwx_key.dylib 并调用
  ScanMemoryForImageKey，通过 JSON stdout 返回结果
- 新建 resources/image_scan_entitlements.plist：包含 debugger 和
  allow-unsigned-executable-memory entitlements
- 编译为 universal binary（x86_64 + arm64）并 ad-hoc 签名
- 修改 keyServiceMac.ts _scanMemoryForAesKey()：优先 spawn
  image_scan_helper 子进程，失败时 fallback 到直接调 dylib

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

electron/services/keyServiceMac.ts

@@ -43,6 +43,26 @@ export class KeyServiceMac {
     throw new Error('xkey_helper not found')
   }
 
+  private getImageScanHelperPath(): string {
+    const isPackaged = app.isPackaged
+    const candidates: string[] = []
+
+    if (isPackaged) {
+      candidates.push(join(process.resourcesPath, 'resources', 'image_scan_helper'))
+      candidates.push(join(process.resourcesPath, 'image_scan_helper'))
+    } else {
+      const cwd = process.cwd()
+      candidates.push(join(cwd, 'resources', 'image_scan_helper'))
+      candidates.push(join(app.getAppPath(), 'resources', 'image_scan_helper'))
+    }
+
+    for (const path of candidates) {
+      if (existsSync(path)) return path
+    }
+
+    throw new Error('image_scan_helper not found')
+  }
+
   private getDylibPath(): string {
     const isPackaged = app.isPackaged
     const candidates: string[] = []
@@ -463,6 +483,36 @@ export class KeyServiceMac {
 
   private async _scanMemoryForAesKey(pid: number, ciphertext: Buffer): Promise<string | null> {
     const ciphertextHex = ciphertext.toString('hex')
+
+    // 优先通过 image_scan_helper 子进程调用（有 debugger entitlement）
+    try {
+      const helperPath = this.getImageScanHelperPath()
+      const result = await new Promise<string | null>((resolve, reject) => {
+        const child = spawn(helperPath, [String(pid), ciphertextHex], { stdio: ['ignore', 'pipe', 'pipe'] })
+        let stdout = ''
+        child.stdout.on('data', (chunk: Buffer) => { stdout += chunk.toString() })
+        child.stderr.on('data', (chunk: Buffer) => { console.log('[image_scan_helper]', chunk.toString().trim()) })
+        child.on('error', reject)
+        child.on('close', () => {
+          try {
+            const lines = stdout.split(/\r?\n/).map(x => x.trim()).filter(Boolean)
+            const last = lines[lines.length - 1]
+            if (!last) { resolve(null); return }
+            const payload = JSON.parse(last)
+            resolve(payload?.success && payload?.aesKey ? payload.aesKey : null)
+          } catch {
+            resolve(null)
+          }
+        })
+        setTimeout(() => { try { child.kill('SIGTERM') } catch {} }, 30_000)
+      })
+      return result
+    } catch (e: any) {
+      console.warn('[KeyServiceMac] image_scan_helper unavailable, fallback to dylib:', e?.message)
+    }
+
+    // fallback: 直接调 dylib（Electron 进程可能没有 task_for_pid 权限）
+    if (!this.initialized) await this.initialize()
     const aesKey = this.ScanMemoryForImageKey(pid, ciphertextHex)
     return aesKey || null
   }

resources/image_scan_entitlements.plist

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+    <key>com.apple.security.cs.debugger</key>
+    <true/>
+    <key>com.apple.security.cs.allow-unsigned-executable-memory</key>
+    <true/>
+</dict>
+</plist>

resources/image_scan_helper.c

@@ -0,0 +1,77 @@
+/*
+ * image_scan_helper - 轻量包装程序
+ * 加载 libwx_key.dylib 并调用 ScanMemoryForImageKey
+ * 用法: image_scan_helper <pid> <ciphertext_hex>
+ * 输出: JSON {"success":true,"aesKey":"..."} 或 {"success":false,"error":"..."}
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <dlfcn.h>
+#include <libgen.h>
+#include <mach-o/dyld.h>
+
+typedef const char* (*ScanMemoryForImageKeyFn)(int pid, const char* ciphertext);
+typedef void (*FreeStringFn)(const char* str);
+
+int main(int argc, char* argv[]) {
+    if (argc != 3) {
+        fprintf(stderr, "Usage: %s <pid> <ciphertext_hex>\n", argv[0]);
+        printf("{\"success\":false,\"error\":\"invalid arguments\"}\n");
+        return 1;
+    }
+
+    int pid = atoi(argv[1]);
+    const char* ciphertext_hex = argv[2];
+
+    if (pid <= 0) {
+        printf("{\"success\":false,\"error\":\"invalid pid\"}\n");
+        return 1;
+    }
+
+    /* 定位 dylib: 与自身同目录下的 libwx_key.dylib */
+    char exe_path[4096];
+    uint32_t size = sizeof(exe_path);
+    if (_NSGetExecutablePath(exe_path, &size) != 0) {
+        printf("{\"success\":false,\"error\":\"cannot get executable path\"}\n");
+        return 1;
+    }
+
+    char* dir = dirname(exe_path);
+    char dylib_path[4096];
+    snprintf(dylib_path, sizeof(dylib_path), "%s/libwx_key.dylib", dir);
+
+    void* handle = dlopen(dylib_path, RTLD_LAZY);
+    if (!handle) {
+        printf("{\"success\":false,\"error\":\"dlopen failed: %s\"}\n", dlerror());
+        return 1;
+    }
+
+    ScanMemoryForImageKeyFn scan_fn = (ScanMemoryForImageKeyFn)dlsym(handle, "ScanMemoryForImageKey");
+    if (!scan_fn) {
+        printf("{\"success\":false,\"error\":\"symbol not found: ScanMemoryForImageKey\"}\n");
+        dlclose(handle);
+        return 1;
+    }
+
+    FreeStringFn free_fn = (FreeStringFn)dlsym(handle, "FreeString");
+
+    fprintf(stderr, "[image_scan_helper] calling ScanMemoryForImageKey(pid=%d, ciphertext=%s)\n", pid, ciphertext_hex);
+
+    const char* result = scan_fn(pid, ciphertext_hex);
+
+    if (result && strlen(result) > 0) {
+        /* 检查是否是错误 */
+        if (strncmp(result, "ERROR", 5) == 0) {
+            printf("{\"success\":false,\"error\":\"%s\"}\n", result);
+        } else {
+            printf("{\"success\":true,\"aesKey\":\"%s\"}\n", result);
+        }
+        if (free_fn) free_fn(result);
+    } else {
+        printf("{\"success\":false,\"error\":\"no key found\"}\n");
+    }
+
+    dlclose(handle);
+    return 0;
+}