chore: remove deploy hook workflow, let Vercel auto-deploy on push (#1046)

VERCEL_DEPLOY_HOOK_NAME is not set for deploy hooks, causing all
builds to be canceled by the ignoreCommand. Simplify by removing
the GitHub Action workflow and ignoreCommand, letting Vercel's
native git integration deploy on every push to main.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: d-bytebase

.github/workflows/deploy.yml

@@ -1,3 +1 @@
-{
-  "ignoreCommand": "if [ -n \"$VERCEL_DEPLOY_HOOK_NAME\" ]; then exit 1; else exit 0; fi"
-}
+{}