feat(backend): boxSettings table + box password actions

packages/backend/convex/schema.ts

@@ -376,6 +376,18 @@ const applicationTables = {
     setupCommand: v.optional(v.string()),
     updatedAt: v.number(),
   }).index('by_owner', ['ownerId']),
+  // Per-user box account settings (the Linux user inside spoon-box-<username>).
+  boxSettings: defineTable({
+    ownerId: v.id('users'),
+    // Resolved Spoon home username at the time the row was written — the
+    // worker looks the password up by this at box creation (usernames are not
+    // indexed anywhere else).
+    username: v.string(),
+    boxPasswordEncrypted: v.optional(v.string()),
+    updatedAt: v.number(),
+  })
+    .index('by_owner', ['ownerId'])
+    .index('by_username', ['username']),
   aiProviderProfiles: defineTable({
     ownerId: v.id('users'),
     name: v.string(),