feat(psa): ticket queue dashboard with board selector and session auto-start

- Add PSABoard type + list_boards() to CW provider (cached 1h)
- Extend search_tickets with assigned_to_me, unassigned, board_ids, page, page_size
- New GET /integrations/psa/boards endpoint
- New TicketQueue dashboard component: My Tickets / Unassigned tabs,
  multi-select board filter, Load more pagination, Start Session per ticket
- Add TicketQueue to QuickStartPage after active sessions
- FlowPilotSessionPage auto-starts with ticket context when navigated
  from TicketQueue (psaTicketId + psaTicket in location.state)

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

backend/app/services/psa/base.py

@@ -12,6 +12,7 @@ from .types import (
     PSAMember,
     PSAConfiguration,
     PSATimeEntry,
+    PSABoard,
 )
 
 
@@ -64,6 +65,10 @@ class PSAProvider(ABC):
     async def list_members(self) -> list[PSAMember]:
         ...
 
+    @abstractmethod
+    async def list_boards(self) -> list[PSABoard]:
+        ...
+
     @abstractmethod
     async def get_ticket_configurations(self, ticket_id: str) -> list[PSAConfiguration]:
         ...