fix(tickets): fix statuses endpoint, members auth gate, and graceful error handling

- Add GET /boards/{board_id}/statuses endpoint — direct board-to-statuses lookup
  without ticket roundabout; used by filter bar and new ticket form
- Fix TicketsPage and NewTicketModal to call getBoardStatuses(board_id) instead
  of misusing getTicketStatuses(ticket_id) with a board_id value
- Fix list_members auth: was require_account_owner (owner/super_admin only) —
  changed to require_engineer_or_admin so engineers can see member list for
  ticket assignment
- list_members: return [] on PSAError instead of 502 (Lesson 111 pattern)
- get_ticket_statuses: return [] on PSAError instead of 502

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/api/endpoints/integrations.py

@@ -788,7 +788,30 @@ async def get_ticket_statuses(
     except PSANotFoundError:
         raise HTTPException(status_code=404, detail="Ticket not found")
     except PSAError as e:
-        raise HTTPException(status_code=502, detail=str(e))
+        logger.warning("get_ticket_statuses(%s) failed: %s", ticket_id, e)
+        return []
+
+
+@router.get("/boards/{board_id}/statuses", response_model=list[PSATicketStatusItem])
+async def get_board_statuses(
+    board_id: int,
+    current_user: Annotated[User, Depends(require_engineer_or_admin)],
+    db: Annotated[AsyncSession, Depends(get_db)],
+):
+    """Get available statuses for a service board directly (no ticket lookup required)."""
+    if not current_user.account_id:
+        raise HTTPException(status_code=400, detail="User has no account")
+
+    from app.services.psa.registry import get_provider_for_account
+    from app.services.psa.exceptions import PSAError
+
+    try:
+        provider = await get_provider_for_account(current_user.account_id, db)
+        statuses = await provider.get_ticket_statuses(board_id)
+        return [PSATicketStatusItem(id=s.id, name=s.name, is_closed=s.is_closed) for s in statuses]
+    except PSAError as e:
+        logger.warning("get_board_statuses(%s) failed: %s", board_id, e)
+        return []
 
 
 # ── member mapping endpoints ─────────────────────────────────────────
@@ -796,7 +819,7 @@ async def get_ticket_statuses(
 
 @router.get("/members", response_model=list[PsaMemberResponse])
 async def list_members(
-    current_user: Annotated[User, Depends(require_account_owner)],
+    current_user: Annotated[User, Depends(require_engineer_or_admin)],
     db: Annotated[AsyncSession, Depends(get_db)],
 ):
     """List CW members (from CW API)."""
@@ -814,7 +837,9 @@ async def list_members(
             for m in members
         ]
     except PSAError as e:
-        raise HTTPException(status_code=502, detail=str(e))
+        # Members are optional display data — degrade gracefully
+        logger.warning("list_members failed: %s", e)
+        return []
 
 
 @router.get("/member-mappings", response_model=list[PsaMemberMappingResponse])