Add AI prompt tool for natural language graph operations

New MCP tool and portal UI for executing natural language instructions
against the memory graph via Ollama (qwen3-coder:30b). Single LLM call
generates a JSON action plan which is executed sequentially.

Supports 8 action types: add_node, update_node, remove_node, add_edge,
remove_edge, bulk_tag, reorganize, query. Actions can reference previous
results via $result[N].field interpolation. Uses /api/chat with few-shot
assistant example, format:json, and temperature:0 for reliable output.

src/server/routes.ts

@@ -166,4 +166,19 @@ router.post('/maintenance/run', async (_req: Request, res: Response) => {
   }
 });
 
+// Prompt — AI-driven natural language instruction
+router.post('/prompt', async (req: Request, res: Response) => {
+  try {
+    const { prompt } = req.body;
+    if (!prompt || typeof prompt !== 'string') {
+      return res.status(400).json({ error: 'prompt is required' });
+    }
+    const { interpretAndExecute } = await import('../core/prompt/interpreter');
+    const result = await interpretAndExecute(prompt);
+    res.json(result);
+  } catch (err: any) {
+    res.status(500).json({ error: err.message });
+  }
+});
+
 export default router;