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

registry/src/actions/validateContract.ts

@@ -0,0 +1,34 @@
+// 驗證 component.contract.yaml 所有必填欄位
+// Requirements: 1.1, 1.2, 11.5
+
+import { ComponentContractSchema } from '../types';
+import type { ComponentContract } from '../types';
+
+export interface ValidateContractResult {
+  valid: boolean;
+  missing_fields: string[];
+  errors: string[];
+  contract?: ComponentContract;
+}
+
+export function validateContract(raw: unknown): ValidateContractResult {
+  const result = ComponentContractSchema.safeParse(raw);
+
+  if (result.success) {
+    return { valid: true, missing_fields: [], errors: [], contract: result.data };
+  }
+
+  const missing_fields: string[] = [];
+  const errors: string[] = [];
+
+  for (const issue of result.error.issues) {
+    const path = issue.path.join('.');
+    if (issue.code === 'invalid_type' && issue.received === 'undefined') {
+      missing_fields.push(path || issue.message);
+    } else {
+      errors.push(path ? `${path}: ${issue.message}` : issue.message);
+    }
+  }
+
+  return { valid: false, missing_fields, errors };
+}