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/sqlite/migrations_template_pinned_regression_test.go

@@ -0,0 +1,59 @@
+package sqlite
+
+import (
+	"context"
+	"path/filepath"
+	"testing"
+
+	"github.com/steveyegge/beads/internal/types"
+)
+
+func TestRunMigrations_DoesNotResetPinnedOrTemplate(t *testing.T) {
+	ctx := context.Background()
+	dir := t.TempDir()
+	dbPath := filepath.Join(dir, "beads.db")
+
+	s, err := New(ctx, dbPath)
+	if err != nil {
+		t.Fatalf("New: %v", err)
+	}
+	t.Cleanup(func() { _ = s.Close() })
+
+	if err := s.SetConfig(ctx, "issue_prefix", "test"); err != nil {
+		t.Fatalf("SetConfig(issue_prefix): %v", err)
+	}
+
+	issue := &types.Issue{
+		Title:      "Pinned template",
+		Status:     types.StatusOpen,
+		Priority:   2,
+		IssueType:  types.TypeTask,
+		Pinned:     true,
+		IsTemplate: true,
+	}
+	if err := s.CreateIssue(ctx, issue, "test-user"); err != nil {
+		t.Fatalf("CreateIssue: %v", err)
+	}
+
+	_ = s.Close()
+
+	s2, err := New(ctx, dbPath)
+	if err != nil {
+		t.Fatalf("New(reopen): %v", err)
+	}
+	defer func() { _ = s2.Close() }()
+
+	got, err := s2.GetIssue(ctx, issue.ID)
+	if err != nil {
+		t.Fatalf("GetIssue: %v", err)
+	}
+	if got == nil {
+		t.Fatalf("expected issue to exist")
+	}
+	if !got.Pinned {
+		t.Fatalf("expected issue to remain pinned")
+	}
+	if !got.IsTemplate {
+		t.Fatalf("expected issue to remain template")
+	}
+}