Add vault secret manager backend with AES-256-GCM encryption

Secrets are encrypted at rest in the database. The derived encryption
key is held in memory only — on reboot, an authorized user must enter
the master password to unlock. Admins can also manually lock the vault.

- vault_config, vault_category, vault_category_permission, vault_entry tables
- AES-256-GCM encryption with PBKDF2-derived key + per-entry IV
- Master password initialize/unlock/lock/change lifecycle
- Category CRUD with role/user permission model (view/edit/admin)
- Entry CRUD with reveal endpoint (POST to avoid caching)
- Secret values never returned in list/detail responses
- vault.view/edit/admin RBAC permissions seeded
- 19 API integration tests covering full lifecycle

packages/backend/src/db/migrations/0025_vault.sql

@@ -0,0 +1,46 @@
+-- Vault secret manager tables
+
+CREATE TABLE vault_config (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  master_key_salt TEXT NOT NULL,
+  master_key_hash TEXT NOT NULL,
+  created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+  updated_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+CREATE TABLE vault_category (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  name VARCHAR(255) NOT NULL,
+  description TEXT,
+  created_by UUID REFERENCES "user"(id),
+  is_public BOOLEAN NOT NULL DEFAULT false,
+  created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+  updated_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+CREATE TABLE vault_category_permission (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  category_id UUID NOT NULL REFERENCES vault_category(id) ON DELETE CASCADE,
+  role_id UUID REFERENCES role(id),
+  user_id UUID REFERENCES "user"(id),
+  access_level storage_folder_access NOT NULL DEFAULT 'view',
+  created_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+CREATE TABLE vault_entry (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  category_id UUID NOT NULL REFERENCES vault_category(id) ON DELETE CASCADE,
+  name VARCHAR(255) NOT NULL,
+  username VARCHAR(255),
+  url VARCHAR(1000),
+  notes TEXT,
+  encrypted_value TEXT,
+  iv TEXT,
+  created_by UUID REFERENCES "user"(id),
+  updated_by UUID REFERENCES "user"(id),
+  created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+  updated_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+CREATE INDEX idx_vault_category_permission_category ON vault_category_permission(category_id);
+CREATE INDEX idx_vault_entry_category ON vault_entry(category_id);

packages/backend/src/db/migrations/meta/_journal.json

@@ -176,6 +176,13 @@
       "when": 1774840000000,
       "tag": "0024_add_traverse_access_level",
       "breakpoints": true
+    },
+    {
+      "idx": 25,
+      "version": "7",
+      "when": 1774850000000,
+      "tag": "0025_vault",
+      "breakpoints": true
     }
   ]
 }