feat(ticket): add claim, add member, persistent management view

- ClaimButton: staff claim/unclaim with log
- AddMemberButton: UserSelect to add member to ticket channel
- TicketManagementView: persistent LayoutView with all 3 buttons
- claimed_by field in TicketData
- Buttons registered as persistent views for bot restart survival

tickets/data.py

@@ -53,6 +53,7 @@ class TicketData:
     created_at: str = ""
     closed_at: str | None = None
     closed_by: int | None = None
+    claimed_by: int | None = None
     messages: list[TicketMessage] = field(default_factory=list)
     reason: str = ""
 
@@ -66,6 +67,7 @@ class TicketData:
             "created_at": self.created_at,
             "closed_at": self.closed_at,
             "closed_by": self.closed_by,
+            "claimed_by": self.claimed_by,
             "messages": [
                 {
                     "author_id": m.author_id,