Add invite request system and Gitea Actions CI/CD pipeline

Invite request feature:
- Public form to request an invite when INVITE_REQUEST_ENABLED=true
- Stores requests in new invite_requests DB table
- Emails admins on new request, emails requester on approve/deny
- Admin panel tab to review, approve, and deny requests
- Approval auto-creates invite code and sends signup link

CI/CD pipeline:
- Build & push Docker image to Gitea registry on release
- Auto-deploy to staging with health check
- Manual workflow_dispatch for production deploys

Also includes client layout/sizing improvements for card grid
and opponent spacing.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/routers/auth.py

@@ -75,6 +75,13 @@ class UpdatePreferencesRequest(BaseModel):
     preferences: dict
 
 
+class InviteRequestBody(BaseModel):
+    """Invite request body."""
+    name: str
+    email: str
+    message: Optional[str] = None
+
+
 class ConvertGuestRequest(BaseModel):
     """Convert guest to user request."""
     guest_id: str
@@ -332,6 +339,7 @@ async def signup_info():
 
     return {
         "invite_required": invite_required,
+        "invite_request_enabled": config.INVITE_REQUEST_ENABLED,
         "open_signups_enabled": open_signups_enabled,
         "daily_limit": config.DAILY_OPEN_SIGNUPS if not unlimited else None,
         "remaining_today": remaining,
@@ -339,6 +347,55 @@ async def signup_info():
     }
 
 
+@router.post("/request-invite")
+async def request_invite(
+    request_body: InviteRequestBody,
+    request: Request,
+):
+    """
+    Public endpoint: submit a request for an invite code.
+
+    Stores the request in the database and notifies admins via email.
+    """
+    if not config.INVITE_REQUEST_ENABLED:
+        raise HTTPException(status_code=404, detail="Invite requests are not enabled")
+
+    if not _admin_service:
+        raise HTTPException(status_code=503, detail="Service not initialized")
+
+    name = request_body.name.strip()
+    email = request_body.email.strip().lower()
+    message = request_body.message.strip() if request_body.message else None
+
+    if not name or len(name) > 100:
+        raise HTTPException(status_code=400, detail="Name is required (max 100 characters)")
+    if not email or "@" not in email:
+        raise HTTPException(status_code=400, detail="Valid email is required")
+
+    client_ip = get_client_ip(request)
+
+    request_id = await _admin_service.create_invite_request(
+        name=name,
+        email=email,
+        message=message,
+        ip_address=client_ip,
+    )
+
+    # Notify admin emails
+    if config.ADMIN_EMAILS:
+        from services.email_service import get_email_service
+        email_service = get_email_service()
+        for admin_email in config.ADMIN_EMAILS:
+            await email_service.send_invite_request_admin_notification(
+                to=admin_email,
+                requester_name=name,
+                requester_email=email,
+                message=message or "",
+            )
+
+    return {"status": "ok", "message": "Your request has been submitted. We'll be in touch!"}
+
+
 @router.post("/verify-email")
 async def verify_email(
     request_body: VerifyEmailRequest,