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>

internal/storage/storage.go

@@ -107,9 +107,10 @@ type Storage interface {
 
 	// Ready Work & Blocking
 	GetReadyWork(ctx context.Context, filter types.WorkFilter) ([]*types.Issue, error)
-	GetBlockedIssues(ctx context.Context) ([]*types.BlockedIssue, error)
+	GetBlockedIssues(ctx context.Context, filter types.WorkFilter) ([]*types.BlockedIssue, error)
 	GetEpicsEligibleForClosure(ctx context.Context) ([]*types.EpicStatus, error)
 	GetStaleIssues(ctx context.Context, filter types.StaleFilter) ([]*types.Issue, error)
+	GetNewlyUnblockedByClose(ctx context.Context, closedIssueID string) ([]*types.Issue, error) // GH#679
 
 	// Events
 	AddComment(ctx context.Context, issueID, actor, comment string) error