Add structured sections and hierarchical navigation

Add --section flag to add/update commands for structured node content,
render sections and inline children in show, and add memory children command.

src/cli/index.ts

@@ -10,6 +10,7 @@ import { removeCommand } from './commands/remove';
 import { graphCommand } from './commands/graph';
 import { serveCommand } from './commands/serve';
 import { decayCommand } from './commands/decay';
+import { childrenCommand } from './commands/children';
 import { closeDb } from '../core/db';
 
 const program = new Command();
@@ -29,6 +30,7 @@ program.addCommand(removeCommand);
 program.addCommand(graphCommand);
 program.addCommand(serveCommand);
 program.addCommand(decayCommand);
+program.addCommand(childrenCommand);
 
 program.hook('postAction', () => {
   closeDb();