chore(workflows): trigger web-deploy on dev push too

PRs land on `dev` (master is blocked by `block-master-pr`), but the
deploy workflow only listened to `master` pushes — so #3853's web/
dependency bumps merged to dev with no Cloudflare deployment ever
running.

Add `dev` to the push branches list. The existing `paths` filter
keeps the deploy from firing on non-web changes, and `workflow_dispatch`
is preserved as the manual fallback.

.github/workflows/web-deploy.yml

@@ -8,7 +8,7 @@ on:
         required: false
         default: ""
   push:
-    branches: [master]
+    branches: [master, dev]
     paths:
       - "web/**"
       - ".github/workflows/web-deploy.yml"