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/wrangler.toml

@@ -1,26 +0,0 @@
-name = "arcrun-builtins"
-main = "src/index.ts"
-compatibility_date = "2025-02-19"
-compatibility_flags = ["nodejs_compat"]
-workers_dev = true
-
-# Service Binding：呼叫 Cypher Executor 執行排程工作流
-[[services]]
-binding = "CYPHER"
-service = "arcrun-cypher-executor"   # 填入你的 cypher-executor Worker 名稱
-
-# KV Store：cron: 前綴 = 排程定義，ai-transform: 前綴 = 編譯後轉換函式
-[[kv_namespaces]]
-binding = "U6U_STORE"
-id = ""   # 填入你的 KV Namespace ID
-
-# Workers AI：ai-transform 零件的 compile 階段使用
-[ai]
-binding = "AI"
-
-# Cron Trigger：每分鐘掃描並執行到期的排程工作流
-[triggers]
-crons = ["* * * * *"]
-
-[vars]
-ENVIRONMENT = "production"