feat: V5 show tables / relationships / indexes list commands

Add the list-all show family as one Command::ShowList { kind }
variant. A read-only worker show_list formats count-headed lists
(reusing do_list_tables / read_all_relationships /
read_table_indexes, so it never drifts from the items panel);
internal __rdbms_* tables excluded. Help + parse-usage entries
added; 10 integration tests in tests/it/show_list.rs.

Mark V5 [x]. Split the singular show relationship/index <name>
detail forms (the [<name>] half) into a new tracked V5a [ ] item
rather than leaving them as an untracked footnote.

src/app.rs

@@ -605,6 +605,15 @@ impl App {
                 self.handle_dsl_explain_success(&command, &plan);
                 Vec::new()
             }
+            AppEvent::DslShowListSucceeded { command, lines } => {
+                // Mark the echo ✓ (ADR-0040), then emit the
+                // worker-formatted list as system output lines.
+                self.note_ok_summary(&command);
+                for line in lines {
+                    self.note_system(line);
+                }
+                Vec::new()
+            }
             AppEvent::DslInsertSucceeded { command, result } => {
                 self.handle_dsl_insert_success(&command, &result);
                 Vec::new()
@@ -2007,6 +2016,9 @@ impl App {
             C::ShowData { name, .. } | C::ShowTable { name } => {
                 (Operation::Query, Some(name.as_str()), None)
             }
+            // A `show <kind>` list spans no single table; a failure
+            // routes through Query with no table fallback.
+            C::ShowList { .. } => (Operation::Query, None, None),
             // A SQL `SELECT` carries only its statement text —
             // no single table name to fall back on. A query
             // failure routes through `Operation::Query`.
@@ -2822,13 +2834,21 @@ mod tests {
 
     #[test]
     fn tab_cycles_forward_through_multi_candidate_set() {
+        // `show ` offers five subcommands in grammar order:
+        // data / table / tables / relationships / indexes (V5).
         let mut app = App::new();
         type_str(&mut app, "show ");
-        app.update(key(KeyCode::Tab));
-        assert_eq!(app.input, "show data");
-        app.update(key(KeyCode::Tab));
-        assert_eq!(app.input, "show table");
-        // Wrap-around.
+        for expected in [
+            "show data",
+            "show table",
+            "show tables",
+            "show relationships",
+            "show indexes",
+        ] {
+            app.update(key(KeyCode::Tab));
+            assert_eq!(app.input, expected);
+        }
+        // Wrap-around back to the first.
         app.update(key(KeyCode::Tab));
         assert_eq!(app.input, "show data");
     }
@@ -2837,12 +2857,11 @@ mod tests {
     fn shift_tab_cycles_backward_starting_from_last() {
         let mut app = App::new();
         type_str(&mut app, "show ");
-        app.update(key(KeyCode::BackTab));
-        assert_eq!(app.input, "show table");
-        app.update(key(KeyCode::BackTab));
-        assert_eq!(app.input, "show data");
-        app.update(key(KeyCode::BackTab));
-        assert_eq!(app.input, "show table");
+        // Backward starts from the last candidate (`indexes`).
+        for expected in ["show indexes", "show relationships", "show tables"] {
+            app.update(key(KeyCode::BackTab));
+            assert_eq!(app.input, expected);
+        }
     }
 
     #[test]