refactor: remove unused bd pin/unpin/hook commands (bd-x0zl)

Analysis found these commands are dead code:
- gt never calls `bd pin` - uses `bd update --status=pinned` instead
- Beads.Pin() wrapper exists but is never called
- bd hook functionality duplicated by gt mol status
- Code comment says "pinned field is cosmetic for bd hook visibility"

Removed:
- cmd/bd/pin.go
- cmd/bd/unpin.go
- cmd/bd/hook.go

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cmd/bd/sync.go

@@ -361,6 +361,9 @@ Use --merge to merge the sync branch back to main branch.`,
 				}
 			}
 
+			// Clear sync state on successful sync (daemon backoff/hints)
+			_ = ClearSyncState(beadsDir)
+
 			fmt.Println("\n✓ Sync complete")
 			return
 		}
@@ -711,6 +714,11 @@ Use --merge to merge the sync branch back to main branch.`,
 				skipFinalFlush = true
 			}
 
+			// Clear sync state on successful sync (daemon backoff/hints)
+			if bd := beads.FindBeadsDir(); bd != "" {
+				_ = ClearSyncState(bd)
+			}
+
 			fmt.Println("\n✓ Sync complete")
 		}
 	},