feat: 添加 Local Vault 加密存储服务

AES-256-GCM 加密 vault，支持 OS keychain 和加密文件回退，
scrypt KDF 密钥派生，64KB secret 上限。

Co-Authored-By: glm-5-turbo <zai-org@claude-code-best.win>

src/utils/localValidate.ts

@@ -0,0 +1,56 @@
+/**
+ * Shared validation utilities for /local-memory and /local-vault input names.
+ *
+ * Both LocalMemoryRecallTool (PR-1) and VaultHttpFetchTool (PR-2) need a
+ * consistent, path-safe, OS-portable key naming scheme. multiStore.ts also
+ * uses validateKey for entry keys after PR-0a key-collision fix.
+ *
+ * Allowed: letters, digits, dot, underscore, hyphen.
+ * Length 1..128.
+ * Rejected:
+ *   - empty / too long
+ *   - any character outside [A-Za-z0-9._-]
+ *   - leading dot (hidden file pattern, e.g. ".gitconfig")
+ *   - Windows reserved device names (NUL, CON, COM1, etc.) — would silently
+ *     write to a device on Windows and lose data
+ */
+
+const KEY_REGEX = /^[A-Za-z0-9._-]+$/
+// Windows treats device names as reserved REGARDLESS of extension —
+// `NUL.txt`, `CON.foo`, `COM1.bak` all alias to the device. So we must
+// match the basename component (everything before the first dot) against
+// the reserved set, not just the entire key.
+const WINDOWS_RESERVED_BASENAME = /^(CON|PRN|AUX|NUL|COM[1-9]|LPT[1-9])$/i
+const MAX_KEY_LENGTH = 128
+
+export function validateKey(key: string): void {
+  if (!key) {
+    throw new Error('Empty key')
+  }
+  if (key.length > MAX_KEY_LENGTH) {
+    throw new Error(`Key too long (max ${MAX_KEY_LENGTH})`)
+  }
+  if (!KEY_REGEX.test(key)) {
+    throw new Error(`Invalid key chars: ${JSON.stringify(key)}`)
+  }
+  if (key.startsWith('.')) {
+    throw new Error('Leading dot forbidden')
+  }
+  // M6 fix: match the basename (pre-dot component) so e.g. NUL.txt and
+  // CON.foo are also rejected. On Windows these still alias to the device
+  // file regardless of extension and would silently lose data.
+  const basenameComponent = key.includes('.') ? key.split('.')[0]! : key
+  if (WINDOWS_RESERVED_BASENAME.test(basenameComponent)) {
+    throw new Error(`Windows reserved name: ${key}`)
+  }
+}
+
+/** Returns true iff key would pass validateKey (no throw). Useful for guards. */
+export function isValidKey(key: string): boolean {
+  try {
+    validateKey(key)
+    return true
+  } catch {
+    return false
+  }
+}