arcrun — AI workflow execution engine (clean history)

Self-hosted 開源：WASM 零件 + recipe + cypher-executor，跑在你自己的 Cloudflare。

此為重建的乾淨歷史起點（移除曾誤 commit 的 GCP SA 金鑰，舊歷史保留在
richblack/arcrun 與本地 backup 分支）。含：
- acr init --self-hosted installer（建 KV/R2 + codeload 拉預編譯 wasm + wrangler deploy + seed recipe）
- recipe push 把關（資料外流提醒 + 打通檢查）
- 19 個正當零件預編譯 wasm（claude_api/km_writer/kbdb_upsert_block 排除：違反 DECISIONS §1）
- CLI / cypher-executor / registry / 完整 SDD

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

registry/examples/error-retry/workflow.yaml

@@ -0,0 +1,43 @@
+name: error_retry
+description: try_catch + wait + retry 模式：外部 API 偶發掛掉時自動重試
+
+flow:
+  - "input >> ON_SUCCESS >> try_call"
+  - "try_call >> ON_SUCCESS >> done"
+  - "try_call >> ON_FAIL >> wait_a_bit"
+  - "wait_a_bit >> ON_SUCCESS >> retry_call"
+  - "retry_call >> ON_SUCCESS >> done"
+  - "retry_call >> ON_FAIL >> final_fail_notify"
+
+config:
+  try_call:
+    component: http_request
+    url: "{{input.target_url}}"
+    method: POST
+    body_json:
+      payload: "{{input.payload}}"
+
+  wait_a_bit:
+    component: wait
+    seconds: 5
+
+  # 第二次嘗試。生產環境通常 retry 2-3 次配指數 backoff
+  retry_call:
+    component: http_request
+    url: "{{input.target_url}}"
+    method: POST
+    body_json:
+      payload: "{{input.payload}}"
+      _retry: 1
+
+  done:
+    component: comp_passthrough
+    # 純記錄成功，下游若需要可繼續鏈
+
+  final_fail_notify:
+    component: telegram
+    chat_id: "{{secret.LEO_TELEGRAM_CHAT_ID}}"
+    text: |
+      ⚠️ workflow {{input.workflow_name}} 兩次重試都失敗
+      target: {{input.target_url}}
+      last error: {{retry_call.error}}