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/components/try_catch/main.go

@@ -0,0 +1,55 @@
+// try_catch — 判斷上游結果是否有 error，決定走 try 或 catch 分支
+//
+//go:build tinygo
+
+package main
+
+import (
+	"encoding/json"
+	"io"
+	"os"
+)
+
+type Input struct {
+	Result json.RawMessage `json:"result"`
+	Error  string          `json:"error"`
+}
+
+func main() {
+	raw, err := io.ReadAll(os.Stdin)
+	if err != nil {
+		writeError("failed to read stdin: " + err.Error())
+		return
+	}
+	var input Input
+	if err := json.Unmarshal(raw, &input); err != nil {
+		writeError("invalid input JSON: " + err.Error())
+		return
+	}
+
+	if input.Error != "" {
+		out, _ := json.Marshal(map[string]interface{}{
+			"success": true,
+			"data": map[string]interface{}{
+				"branch": "catch",
+				"error":  input.Error,
+			},
+		})
+		os.Stdout.Write(out)
+		return
+	}
+
+	out, _ := json.Marshal(map[string]interface{}{
+		"success": true,
+		"data": map[string]interface{}{
+			"branch": "try",
+			"result": input.Result,
+		},
+	})
+	os.Stdout.Write(out)
+}
+
+func writeError(msg string) {
+	out, _ := json.Marshal(map[string]interface{}{"success": false, "error": msg})
+	os.Stdout.Write(out)
+}