refactor(crypto): make system-wrapped DEKs the authoritative key path

DataCrypto and AuthManager now read keys through UserKeyManager: DEKs are
always unwrappable server-side, so the in-memory unlock session, DEK-in-JWT
wrapping, session-expiry data locks and ALLOW_APIKEY_DATA_UNLOCK are gone.
utils/user-crypto.ts is deleted; boot migration now cleans legacy wraps.
A one-release shim adopts DEKs from legacy dataKeyWrap tokens so active
password users migrate without re-login. Password login migrates legacy
password-wrapped DEKs via migratePasswordUserAtLogin.

src/backend/ssh/opkssh-auth.ts

@@ -4,7 +4,7 @@ import { WebSocket } from "ws";
 import { OPKSSHBinaryManager } from "../utils/opkssh-binary-manager.js";
 import { sshLogger } from "../utils/logger.js";
 import { createCurrentOpksshTokenRepository } from "../database/repositories/factory.js";
-import { UserCrypto } from "../utils/user-crypto.js";
+import { DataCrypto } from "../utils/data-crypto.js";
 import { FieldCrypto } from "../utils/field-crypto.js";
 import { promises as fs } from "fs";
 import path from "path";
@@ -647,12 +647,10 @@ function handleOPKSSHOutput(requestId: string, output: string): void {
 
 async function storeOPKSSHToken(session: OPKSSHAuthSession): Promise<void> {
   try {
-    const userCrypto = UserCrypto.getInstance();
-
     const expiresAt = new Date();
     expiresAt.setHours(expiresAt.getHours() + 24);
 
-    const userDataKey = userCrypto.getUserDataKey(session.userId);
+    const userDataKey = DataCrypto.getUserDataKey(session.userId);
     if (!userDataKey) {
       throw new Error("User data key not found");
     }
@@ -729,8 +727,7 @@ export async function getOPKSSHToken(
       return null;
     }
 
-    const userCrypto = UserCrypto.getInstance();
-    const userDataKey = userCrypto.getUserDataKey(userId);
+    const userDataKey = DataCrypto.getUserDataKey(userId);
     if (!userDataKey) {
       throw new Error("User data key not found");
     }

src/backend/ssh/terminal.ts

@@ -11,7 +11,7 @@ import { createCurrentHostResolutionRepository } from "../database/repositories/
 import { sshLogger, authLogger } from "../utils/logger.js";
 import { logAudit } from "../utils/audit-logger.js";
 import { AuthManager } from "../utils/auth-manager.js";
-import { UserCrypto } from "../utils/user-crypto.js";
+import { DataCrypto } from "../utils/data-crypto.js";
 import {
   createSocks5Connection,
   type SOCKS5Config,
@@ -98,7 +98,6 @@ interface WebSocketMessage {
 }
 
 const authManager = AuthManager.getInstance();
-const userCrypto = UserCrypto.getInstance();
 
 const userConnections = new Map<string, Set<WebSocket>>();
 
@@ -158,7 +157,7 @@ wss.on("connection", async (ws: WebSocket, req) => {
     return;
   }
 
-  const dataKey = userCrypto.getUserDataKey(userId);
+  const dataKey = DataCrypto.getUserDataKey(userId);
   if (!dataKey) {
     ws.send(
       JSON.stringify({
@@ -268,7 +267,7 @@ wss.on("connection", async (ws: WebSocket, req) => {
   }
 
   ws.on("message", async (msg: RawData) => {
-    const currentDataKey = userCrypto.getUserDataKey(userId);
+    const currentDataKey = DataCrypto.getUserDataKey(userId);
     if (!currentDataKey) {
       ws.send(
         JSON.stringify({

src/backend/ssh/vault-signer-auth.ts

@@ -17,7 +17,7 @@
 // is re-exported here so callers have a single import surface.
 
 import { createCurrentVaultTokenRepository } from "../database/repositories/factory.js";
-import { UserCrypto } from "../utils/user-crypto.js";
+import { DataCrypto } from "../utils/data-crypto.js";
 import { FieldCrypto } from "../utils/field-crypto.js";
 import { parseCertValidBefore } from "./vault-signer-core.js";
 
@@ -50,7 +50,7 @@ export async function storeVaultCert(
   privateKey: string,
   signedCert: string,
 ): Promise<string> {
-  const userDataKey = UserCrypto.getInstance().getUserDataKey(userId);
+  const userDataKey = DataCrypto.getUserDataKey(userId);
   if (!userDataKey) {
     throw new Error("User data key not found");
   }
@@ -104,7 +104,7 @@ export async function getVaultCert(
     return null;
   }
 
-  const userDataKey = UserCrypto.getInstance().getUserDataKey(userId);
+  const userDataKey = DataCrypto.getUserDataKey(userId);
   if (!userDataKey) {
     throw new Error("User data key not found");
   }