feat: bd list defaults to non-closed issues with 50 limit (GH#788)

Changes:
- Default to excluding closed issues (use --all to include)
- Default limit of 50 issues (use --limit 0 for unlimited)
- --all flag now overrides the closed filter

This addresses agent context blowout from seeing hundreds of closed issues.

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

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

internal/rpc/protocol.go

@@ -208,6 +208,9 @@ type ListArgs struct {
 
 	// Molecule type filtering
 	MolType string `json:"mol_type,omitempty"`
+
+	// Status exclusion (for default non-closed behavior, GH#788)
+	ExcludeStatus []string `json:"exclude_status,omitempty"`
 }
 
 // CountArgs represents arguments for the count operation

internal/rpc/server_issues_epics.go

@@ -980,6 +980,13 @@ func (s *Server) handleList(req *Request) Response {
 		filter.MolType = &molType
 	}
 
+	// Status exclusion (for default non-closed behavior, GH#788)
+	if len(listArgs.ExcludeStatus) > 0 {
+		for _, s := range listArgs.ExcludeStatus {
+			filter.ExcludeStatus = append(filter.ExcludeStatus, types.Status(s))
+		}
+	}
+
 	// Guard against excessive ID lists to avoid SQLite parameter limits
 	const maxIDs = 1000
 	if len(filter.IDs) > maxIDs {