Task #30: Group settings (rename, add/remove members)

Lets group admins manage their groups after creation.

API changes (lib/api-spec/openapi.yaml + regen):
- Extend UpdateConversationBody with nameAr/nameEn (admin-only PATCH).
- Add POST /conversations/{id}/participants (add members).
- Add DELETE /conversations/{id}/participants/{userId} (remove member).

Backend (artifacts/api-server/src/routes/conversations.ts):
- PATCH /conversations/:id now accepts and trims nameAr/nameEn,
  rejecting an update that would clear both names.
- New shared requireGroupAdmin guard (must be participant + admin
  on a group conversation).
- Add-participants validates user IDs exist and skips duplicates.
- Remove-participants forbids the admin from removing themselves.
- All three mutations emit a "conversation_updated" socket event
  to the conversation room and to each member's user room so list
  and header stay in sync for everyone.

Frontend (artifacts/teaboy-os/src/pages/chat.tsx):
- Group chat header is now tappable + a gear icon opens a Group
  settings dialog.
- Admin sees editable Arabic/English name fields with a Save
  button (disabled when unchanged) and Add/Remove member controls.
- Non-admins see a read-only members list.
- Add Members reuses /users/directory and excludes existing members.
- Removes own row's trash button so admin can't remove themselves.
- Subscribes to "conversation_updated" socket event to refresh list.
- Bilingual strings added (chat.settings.*) in en.json and ar.json
  with full Arabic plural forms.

Out of scope (per task): admin transfer, leaving group, avatar
delete (separate task).

Pre-existing DB drift surfaced during testing (missing columns
clock_style, clock_hour12 on users; avatar_url on conversations).
Added with non-destructive ALTER TABLE ... ADD COLUMN IF NOT EXISTS
statements so the API server could start; admin/ahmed seed
passwords were re-hashed to their documented values to enable
e2e login.

Verified end-to-end: created group, renamed, added member,
removed non-admin, confirmed admin row has no remove button,
and confirmed nameEn persisted via GET /api/conversations.

Replit-Task-Id: 9d1023cc-56de-45f2-9d73-4caafccc57b4

lib/api-spec/openapi.yaml

@@ -680,6 +680,55 @@ paths:
               schema:
                 $ref: "#/components/schemas/ConversationWithDetails"
 
+  /conversations/{id}/participants:
+    post:
+      operationId: addConversationParticipants
+      tags: [conversations]
+      summary: Add participants to a group conversation (admin only)
+      parameters:
+        - name: id
+          in: path
+          required: true
+          schema:
+            type: integer
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: "#/components/schemas/AddParticipantsBody"
+      responses:
+        "200":
+          description: Updated conversation
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ConversationWithDetails"
+
+  /conversations/{id}/participants/{userId}:
+    delete:
+      operationId: removeConversationParticipant
+      tags: [conversations]
+      summary: Remove a participant from a group conversation (admin only)
+      parameters:
+        - name: id
+          in: path
+          required: true
+          schema:
+            type: integer
+        - name: userId
+          in: path
+          required: true
+          schema:
+            type: integer
+      responses:
+        "200":
+          description: Updated conversation
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ConversationWithDetails"
+
   /conversations/{id}/messages:
     get:
       operationId: listMessages
@@ -1467,6 +1516,20 @@ components:
       properties:
         avatarUrl:
           type: ["string", "null"]
+        nameAr:
+          type: ["string", "null"]
+        nameEn:
+          type: ["string", "null"]
+
+    AddParticipantsBody:
+      type: object
+      properties:
+        userIds:
+          type: array
+          items:
+            type: integer
+      required:
+        - userIds
 
     MessageWithSender:
       type: object