fix(arcrun): address PR #2 review findings

Security:
- init.ts: remove cf_api_token from POST /register (only email sent to arcrun.dev)
- cf-api.ts: remove base64 fallback in encryptCredential, throw clear error if key missing

Correctness:
- submitComponent.ts: replace KBDB dependency with SUBMISSIONS_KV + R2 (standalone)
- registry/types.ts: remove KBDB_URL/KBDB_INTERNAL_TOKEN, add SUBMISSIONS_KV/ANALYTICS_KV
- webhooks.ts: add waitUntil(writeExecutionVerdict) for fire-and-forget analytics
- execution-logger.ts: create missing module (was imported but didn't exist)
- cypher-executor/types.ts + wrangler.toml: add ANALYTICS_KV binding
- gmail/telegram/google_sheets/line_notify/http_request: no_network_syscall false (api category)
- init.ts: replace require() with await import() for ES module compatibility

Cleanup:
- Remove arcrun/builtins/ (dead code — initComponents used old HTTP endpoint model,
  all 21 components now in TinyGo WASM under registry/components/)

Docs:
- tasks.md: update to reflect completed work and remaining items

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

builtins/src/index.ts

@@ -1,27 +0,0 @@
-// u6u-builtins Worker
-// 所有零件已遷移至 u6u-core/registry/components/ 的 TinyGo .wasm 版本
-// 此 Worker 保留 /init 端點供初始化 Component Registry 使用
-
-import { Hono } from 'hono';
-import { cors } from 'hono/cors';
-import type { Bindings } from './types';
-import { initComponents } from './actions/initComponents';
-
-const app = new Hono<{ Bindings: Bindings }>();
-app.use('*', cors());
-
-app.get('/', c => c.json({
-  service: 'u6u-builtins',
-  version: '2.0.0',
-  status: 'ok',
-  note: '所有零件已遷移至 WASM，請使用 Component Registry',
-}));
-
-// POST /init — 把所有零件上架到 Component Registry（冪等，可重複執行）
-app.post('/init', async c => {
-  const result = await initComponents(c.env);
-  const allOk = result.failed === 0;
-  return c.json({ success: allOk, ...result }, allOk ? 200 : 207);
-});
-
-export default app;