feat(arcrun): implement arcrun MVP — open-source AI workflow engine

Phase 1-5 complete per .agents/specs/u6u-core-mvp/:

**Phase 1 — Cherry-pick & cleanup**
- Create arcrun/ from cypher-executor, credentials, builtins, registry
- Remove 9 InkStone Service Bindings (KBDB, REGISTRY, CLINIC_*, AICEO, MINI_ME)
- Rewrite component-loader: 3-layer (builtin → WASM_BUCKET R2 → error)
- Remove autoPublishMissing.ts, proxy.ts (AICEO), execution-logger.ts (KBDB)
- Clean all KV namespace IDs and InkStone internal URLs from config files

**Phase 2 — contract.yaml completeness**
- Add credentials_required to gmail, google_sheets, telegram, line_notify
- Add config_example to all 21 components with annotated field descriptions

**Phase 3 — Credential injection**
- Add credential-injector.ts: AES-GCM decrypt from CREDENTIALS_KV
- Integrate into GraphExecutor before WASM execution
- Structured errors with repair instructions when credential missing

**Phase 4 — CLI (acr)**
- cli/package.json: arcrun package, bin: acr, deps: commander/js-yaml/chalk/ora
- 8 commands: init, creds push, push, run, validate, parts, list, logs
- Standard mode: writes directly to user's CF KV via CF REST API
- acr init: interactive setup with arcrun.dev API Key registration

**Phase 5 — Open source release prep**
- README.md: 5-minute quickstart, component table, workflow YAML syntax
- CONTRIBUTING.md: TinyGo dev env, component scaffolding, submission flow
- Security audit: no InkStone internal URLs/IDs in committed files
- .gitignore: exclude credentials.yaml, .wrangler, *.wasm

https://claude.ai/code/session_01BnCdSLVH8tUed9VrrPavgT

cypher-executor/src/actions/graph-builder.ts

@@ -0,0 +1,30 @@
+import type { ParsedTriplets } from './triplet-parser';
+import { toEdgeType } from './triplet-parser';
+import type { SearchResult } from './search-nodes';
+
+/** 從 nodeResults + parsed 組成可直接送入 /execute 的 ExecutionGraph */
+export function buildExecutionGraph(
+  parsed: ParsedTriplets,
+  nodeResults: SearchResult['nodeResults'],
+  graphId: string,
+  graphName: string,
+) {
+  const nodes = [...parsed.nodeNames].map(name => {
+    const nr = nodeResults[name]!;
+    const id = name.toLowerCase().replace(/\s+/g, '-');
+    return {
+      id,
+      type: nr.type,
+      componentId: nr.componentId,
+      label: name,
+    };
+  });
+
+  const edges = parsed.edges.map(e => ({
+    from: e.from.toLowerCase().replace(/\s+/g, '-'),
+    to: e.to.toLowerCase().replace(/\s+/g, '-'),
+    type: toEdgeType(e.label),
+  }));
+
+  return { id: graphId, name: graphName, nodes, edges };
+}