feat: KBDB-graph 插件獨立 — 全面改寫成走基本盤 API（API-as-Wall）

按 leo 鐵律（2026-06-14）把插件從「直接 SQL 操作基本盤表」改寫成
「只透過基本盤 arcrun/kbdb HTTP API 讀寫」。零建表、零 migration、零 SQL。

- 新增 src/lib/kbdb-client.ts：唯一對外通道，封裝 entries/templates/records API
- 新增 src/lib/templates.ts：triplet/entity template 定義（替代建表）
- 改寫 21 個違規 action（triplet/graph/entity/search）→ 走 client，圖在插件層記憶體組裝
- 移除所有 migrations、D1/Vectorize/AI 綁定；embedding/語意搜尋歸基本盤 optional 模組
- index.ts 只掛 triplets/graph/entities/search 路由；基本盤路由歸 arcrun/kbdb
- 測試改走 mock client（純 node）；裁剪 CLAUDE.md 只留 graph 插件 + 鐵律
- 修正 SDD design.md「讀現狀推翻鐵律」的錯誤判斷（共用 D1 → API-as-Wall）

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/actions/triplet-entities.ts

@@ -0,0 +1,57 @@
+// 列出所有唯一實體（subject ∪ object）— 零 SQL / 零 D1
+// 取全部 triplet record（走基本盤 API），在記憶體統計 as_subject/as_object/total。
+// GET /entities
+
+import type { KbdbClient } from '../lib/kbdb-client';
+import { queryTriplets } from './triplet-crud';
+
+export interface EntityStat {
+  name: string;
+  as_subject: number;
+  as_object: number;
+  total: number;
+}
+
+export interface EntityListResult {
+  entities: EntityStat[];
+  total: number;
+  limit: number;
+  offset: number;
+}
+
+export async function listTripletEntities(
+  client: KbdbClient,
+  { limit = 200, offset = 0, q }: { limit?: number; offset?: number; q?: string },
+): Promise<EntityListResult> {
+  const safeLimit = Math.min(limit, 500);
+  const { triplets } = await queryTriplets(client, { limit: 2000 });
+
+  const stats = new Map<string, EntityStat>();
+  const bump = (name: string, role: 'as_subject' | 'as_object') => {
+    if (!name) return;
+    let s = stats.get(name);
+    if (!s) {
+      s = { name, as_subject: 0, as_object: 0, total: 0 };
+      stats.set(name, s);
+    }
+    s[role] += 1;
+    s.total += 1;
+  };
+
+  for (const t of triplets) {
+    bump(t.subject, 'as_subject');
+    bump(t.object, 'as_object');
+  }
+
+  let entities = [...stats.values()];
+  if (q) {
+    const needle = q.toLowerCase();
+    entities = entities.filter((e) => e.name.toLowerCase().includes(needle));
+  }
+  entities.sort((a, b) => b.total - a.total);
+
+  const total = entities.length;
+  const page = entities.slice(offset, offset + safeLimit);
+
+  return { entities: page, total, limit: safeLimit, offset };
+}