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.

portal/src/components/PromptPanel.tsx

@@ -0,0 +1,137 @@
+import { useState } from 'react';
+import { api } from '../api';
+import type { PromptResult } from '../types';
+
+interface Props {
+  onClose: () => void;
+  onDone: () => void;
+}
+
+export default function PromptPanel({ onClose, onDone }: Props) {
+  const [text, setText] = useState('');
+  const [result, setResult] = useState<PromptResult | null>(null);
+  const [loading, setLoading] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+
+  const submit = async () => {
+    if (!text.trim()) return;
+    setLoading(true);
+    setError(null);
+    setResult(null);
+    try {
+      const data = await api.prompt(text);
+      setResult(data);
+      if (data.success) onDone();
+    } catch (err: any) {
+      setError(err.message || 'Request failed');
+    } finally {
+      setLoading(false);
+    }
+  };
+
+  return (
+    <div className="h-full flex flex-col bg-gray-900/95 backdrop-blur border-t border-amber-500/30 rounded-t-xl">
+      {/* Header */}
+      <div className="flex items-center justify-between px-4 py-3 border-b border-gray-700/50">
+        <span className="text-amber-300 font-medium text-sm">AI Prompt</span>
+        <button onClick={onClose} className="text-gray-500 hover:text-gray-300 text-lg">&times;</button>
+      </div>
+
+      {/* Input */}
+      <div className="px-4 py-3 flex gap-2">
+        <input
+          value={text}
+          onChange={e => setText(e.target.value)}
+          onKeyDown={e => e.key === 'Enter' && !loading && submit()}
+          placeholder='e.g. "create a decision node about using Redis for caching"'
+          className="flex-1 bg-gray-800 border border-gray-600 rounded-lg px-3 py-2 text-sm text-gray-200 placeholder-gray-500 focus:outline-none focus:border-amber-500"
+          autoFocus
+          disabled={loading}
+        />
+        <button
+          onClick={submit}
+          disabled={loading || !text.trim()}
+          className="px-4 py-2 bg-amber-600 hover:bg-amber-500 disabled:opacity-50 rounded-lg text-sm text-white font-medium min-w-[80px]"
+        >
+          {loading ? (
+            <span className="inline-block animate-pulse">Running...</span>
+          ) : 'Run'}
+        </button>
+      </div>
+
+      {/* Results */}
+      <div className="flex-1 overflow-y-auto px-4 pb-4">
+        {!result && !loading && !error && (
+          <div className="text-gray-500 text-sm mt-4 space-y-1">
+            <p>Give a natural language instruction to modify the graph:</p>
+            <p className="text-gray-600 ml-2">"create a decision node about using Redis for caching"</p>
+            <p className="text-gray-600 ml-2">"tag all task nodes with 'backlog'"</p>
+            <p className="text-gray-600 ml-2">"create a component for auth and link it to the API gateway"</p>
+          </div>
+        )}
+
+        {loading && (
+          <div className="text-amber-400/70 text-sm mt-4 animate-pulse">
+            Generating and executing action plan...
+          </div>
+        )}
+
+        {error && (
+          <div className="mt-4 p-3 rounded-lg bg-red-900/30 border border-red-700/50 text-red-300 text-sm">
+            {error}
+          </div>
+        )}
+
+        {result && (
+          <div className="space-y-3 mt-2">
+            {/* Summary */}
+            <div className={`p-3 rounded-lg border text-sm ${
+              result.success
+                ? 'bg-green-900/20 border-green-700/50 text-green-300'
+                : 'bg-yellow-900/20 border-yellow-700/50 text-yellow-300'
+            }`}>
+              <div className="font-medium mb-1">{result.success ? 'Completed' : 'Completed with errors'}</div>
+              <div>{result.summary}</div>
+            </div>
+
+            {/* Reasoning */}
+            {result.reasoning && (
+              <div className="text-xs text-gray-400 bg-gray-800/50 rounded-lg p-3">
+                <span className="text-gray-500 font-medium">Reasoning: </span>
+                {result.reasoning}
+              </div>
+            )}
+
+            {/* Execution log */}
+            {result.executionLog.length > 0 && (
+              <div className="space-y-1">
+                <div className="text-xs text-gray-500 font-medium uppercase tracking-wide">Execution Log</div>
+                {result.executionLog.map((entry, i) => (
+                  <div
+                    key={i}
+                    className={`flex items-start gap-2 p-2 rounded text-sm ${
+                      entry.status === 'completed' ? 'bg-gray-800/30' : 'bg-red-900/20'
+                    }`}
+                  >
+                    <span className={`mt-0.5 text-xs ${
+                      entry.status === 'completed' ? 'text-green-500' : 'text-red-500'
+                    }`}>
+                      {entry.status === 'completed' ? '✓' : '✗'}
+                    </span>
+                    <div className="flex-1 min-w-0">
+                      <div className="text-gray-300 truncate">{entry.description}</div>
+                      <div className="text-xs text-gray-500">{entry.action}</div>
+                      {entry.error && (
+                        <div className="text-xs text-red-400 mt-1">{entry.error}</div>
+                      )}
+                    </div>
+                  </div>
+                ))}
+              </div>
+            )}
+          </div>
+        )}
+      </div>
+    </div>
+  );
+}