feat: add /register endpoint + fix acr run Mode 1 (inline YAML execution)

- POST /register on cypher.arcrun.dev: HMAC-SHA256(email, ENCRYPTION_KEY) → ak_{32hex}, no DB needed
- acr run: Mode 1 (standard/local) now finds local YAML and POSTs to /cypher/execute inline
- acr init: fix register URL → cypher.arcrun.dev/register; fix local mode description
- acr init --local: creates hello.yaml example workflow
- cli v1.0.3 published

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cli/package.json

@@ -1,6 +1,6 @@
 {
   "name": "arcrun",
-  "version": "1.0.2",
+  "version": "1.0.3",
   "description": "AI Workflow CLI for arcrun — deploy and run WASM-based AI workflows on Cloudflare",
   "bin": {
     "acr": "dist/index.js"