fix: Exclude workflow types from bd ready by default (gt-7xtn)

merge-request, gate, molecule, and message types are internal workflow
items processed by Refinery/Deacon, not work for polecats to claim.
These are now excluded from bd ready unless explicitly requested via
--type flag.

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

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

internal/storage/memory/memory.go

@@ -935,6 +935,20 @@ func (m *MemoryStorage) GetReadyWork(ctx context.Context, filter types.WorkFilte
 			continue
 		}
 
+		// Type filtering (gt-7xtn)
+		if filter.Type != "" {
+			if string(issue.IssueType) != filter.Type {
+				continue
+			}
+		} else {
+			// Exclude workflow types from ready work by default
+			// These are internal workflow items, not work for polecats to claim
+			switch issue.IssueType {
+			case types.TypeMergeRequest, types.TypeGate, types.TypeMolecule, types.TypeMessage:
+				continue
+			}
+		}
+
 		// Unassigned takes precedence over Assignee filter
 		if filter.Unassigned {
 			if issue.Assignee != "" {

internal/storage/sqlite/ready.go

@@ -33,6 +33,14 @@ func (s *SQLiteStorage) GetReadyWork(ctx context.Context, filter types.WorkFilte
 	if filter.Type != "" {
 		whereClauses = append(whereClauses, "i.issue_type = ?")
 		args = append(args, filter.Type)
+	} else {
+		// Exclude workflow types from ready work by default (gt-7xtn)
+		// These are internal workflow items, not work for polecats to claim:
+		// - merge-request: processed by Refinery
+		// - gate: async wait conditions
+		// - molecule: workflow containers
+		// - message: mail/communication items
+		whereClauses = append(whereClauses, "i.issue_type NOT IN ('merge-request', 'gate', 'molecule', 'message')")
 	}
 
 	if filter.Priority != nil {