feat(v0.3): add Projects filter to ListWorkspaces; fix last/delete

ListOpts gains a Projects bool that filters by EffectiveType.
Default behavior (Projects: false) now returns tasks only --
this is a deliberate semantic change that supports the new
'ctask list' (tasks) vs 'ctask list --projects' (projects)
spec.

The change silently regresses two cmd-level callers that scan
for "the most recently updated workspace": cmd/last.go (used by
'ctask last') and cmd/delete.go (used to print the "this was
your most recent workspace" note). Both are fixed by unioning a
tasks-scan with a projects-scan, so 'last' and 'delete' continue
to consider both types.

Test helper createTestWorkspaceTyped allows setting an explicit
type (or "" to simulate a v0.2 workspace with no type field).

cmd/delete.go

@@ -70,11 +70,18 @@ func runDelete(cmd *cobra.Command, args []string) error {
 	fmt.Printf("  Workspace: %s\n", relPath)
 	fmt.Printf("  Files: %d (%s)\n", fileCount, formatSize(totalSize))
 
-	// Check if this is the most recently updated workspace
-	results, _ := workspace.ListWorkspaces(root, workspace.ListOpts{
+	// Check if this is the most recently updated workspace.
+	// v0.3: union tasks and projects so the "most recent" check spans both types.
+	tasks, _ := workspace.ListWorkspaces(root, workspace.ListOpts{
 		IncludeArchived: false,
 		Limit:           0,
 	})
+	projects, _ := workspace.ListWorkspaces(root, workspace.ListOpts{
+		IncludeArchived: false,
+		Projects:        true,
+		Limit:           0,
+	})
+	results := append(tasks, projects...)
 	if len(results) > 0 {
 		best := results[0]
 		for _, r := range results[1:] {