Fix Woodpecker event name: deployment, not deploy

Caught from the linter warnings on the first real pipeline run (#1) — the
production-promotion step's event filter used \`deploy\`, an invalid event
name, so it would never have matched Woodpecker's actual deploy-button
event (\`deployment\`) and the production step would have silently never
run. Staging's own deploy (a push-triggered step) was unaffected and
verified working on that same run.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017DUU6CnxECCDeqDNYJgr5x

deployment-plan.md

@@ -121,7 +121,7 @@ revisited and simplified to auto-deploy staging instead.
 **Actual flow**: any push (any branch) runs lint + typecheck, then
 auto-deploys to a shared staging environment — no button needed. Production
 is never touched automatically; promoting to it is a manual **Deploy**
-button click (Woodpecker's built-in deploy event) on a `main`-branch
+button click (Woodpecker's built-in `deployment` event) on a `main`-branch
 pipeline run, typing `production` as the deploy target
 (`$CI_PIPELINE_DEPLOY_TARGET`). Requires **"Allow deployments"** enabled in
 the repo's Woodpecker project settings.