feat(sns): 增强朋友圈时间线/媒体获取与实时同步

- 新增 /api/sns/users：按发圈数统计联系人（支持 keyword/limit）
- 新增 /api/sns/realtime/sync_latest：WCDB 实时增量同步到解密库（append-only），并持久化 sync state
- 朋友圈媒体优先走“远程下载+解密”：图片支持 wcdb_decrypt_sns_image，视频/实况支持 ISAAC64（WeFlow 逻辑）
- 增加 WeFlow WASM keystream(Node) 优先 + Python ISAAC64 fallback，提升兼容性
- wcdb_api.dll 支持多路径自动发现/环境变量覆盖，并在状态信息中回传实际使用路径

tools/weflow_wasm_keystream.js

@@ -0,0 +1,122 @@
+// Generate WeChat/WeFlow WxIsaac64 keystream via WeFlow's WASM module.
+//
+// Usage:
+//   node tools/weflow_wasm_keystream.js <key> <size>
+//
+// Prints a base64-encoded keystream to stdout (no extra logs).
+
+const fs = require('fs')
+const path = require('path')
+const vm = require('vm')
+
+function usageAndExit() {
+  process.stderr.write('Usage: node tools/weflow_wasm_keystream.js <key> <size>\\n')
+  process.exit(2)
+}
+
+const key = String(process.argv[2] || '').trim()
+const size = Number(process.argv[3] || 0)
+
+if (!key || !Number.isFinite(size) || size <= 0) usageAndExit()
+
+const basePath = path.join(__dirname, '..', 'WeFlow', 'electron', 'assets', 'wasm')
+const wasmPath = path.join(basePath, 'wasm_video_decode.wasm')
+const jsPath = path.join(basePath, 'wasm_video_decode.js')
+
+if (!fs.existsSync(wasmPath) || !fs.existsSync(jsPath)) {
+  process.stderr.write(`WeFlow WASM assets not found: ${basePath}\\n`)
+  process.exit(1)
+}
+
+const wasmBinary = fs.readFileSync(wasmPath)
+const jsContent = fs.readFileSync(jsPath, 'utf8')
+
+let capturedKeystream = null
+let resolveInit
+let rejectInit
+const initPromise = new Promise((res, rej) => {
+  resolveInit = res
+  rejectInit = rej
+})
+
+const mockGlobal = {
+  console: { log: () => {}, error: () => {} }, // keep stdout clean
+  Buffer,
+  Uint8Array,
+  Int8Array,
+  Uint16Array,
+  Int16Array,
+  Uint32Array,
+  Int32Array,
+  Float32Array,
+  Float64Array,
+  BigInt64Array,
+  BigUint64Array,
+  Array,
+  Object,
+  Function,
+  String,
+  Number,
+  Boolean,
+  Error,
+  Promise,
+  require,
+  process,
+  setTimeout,
+  clearTimeout,
+  setInterval,
+  clearInterval,
+}
+
+mockGlobal.Module = {
+  onRuntimeInitialized: () => resolveInit(),
+  wasmBinary,
+  print: () => {},
+  printErr: () => {},
+}
+
+mockGlobal.self = mockGlobal
+mockGlobal.self.location = { href: jsPath }
+mockGlobal.WorkerGlobalScope = function () {}
+mockGlobal.VTS_WASM_URL = `file://${wasmPath}`
+
+mockGlobal.wasm_isaac_generate = (ptr, n) => {
+  const buf = new Uint8Array(mockGlobal.Module.HEAPU8.buffer, ptr, n)
+  capturedKeystream = new Uint8Array(buf) // copy view
+}
+
+try {
+  const context = vm.createContext(mockGlobal)
+  new vm.Script(jsContent, { filename: jsPath }).runInContext(context)
+} catch (e) {
+  rejectInit(e)
+}
+
+;(async () => {
+  try {
+    await initPromise
+
+    if (!mockGlobal.Module.WxIsaac64 && mockGlobal.Module.asm && mockGlobal.Module.asm.WxIsaac64) {
+      mockGlobal.Module.WxIsaac64 = mockGlobal.Module.asm.WxIsaac64
+    }
+    if (!mockGlobal.Module.WxIsaac64) {
+      throw new Error('WxIsaac64 not found in WASM module')
+    }
+
+    capturedKeystream = null
+    const isaac = new mockGlobal.Module.WxIsaac64(key)
+    isaac.generate(size)
+    if (isaac.delete) isaac.delete()
+
+    if (!capturedKeystream) throw new Error('Failed to capture keystream')
+
+    const out = Buffer.from(capturedKeystream)
+    // Match WeFlow worker logic: reverse the captured Uint8Array.
+    out.reverse()
+    process.stdout.write(out.toString('base64'))
+  } catch (e) {
+    process.stderr.write(String(e && e.stack ? e.stack : e) + '\\n')
+    process.exit(1)
+  }
+})()
+