feat: task trash, triage trash and retention settings for every area; admin can forbid keeping things for good

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/api/mcp.go

@@ -550,7 +550,7 @@ var mcpTools = []mcpTool{
 	},
 	{
 		Name:        "delete_task",
-		Description: "Delete a task for good, e.g. one created by mistake. Prefer complete_task for work that is done.",
+		Description: "Delete a task, e.g. one created by mistake: it goes to the task trash, where the user can restore it. Prefer complete_task for work that is done.",
 		Scope:       storage.ScopeTasksWrite,
 		Schema:      schema([]string{"id"}, map[string]interface{}{"id": prop("string", "Task id")}),
 		run: func(s *Server, userID string, actor *apiActor, args json.RawMessage) (interface{}, error) {