ci: use the github context for the WIP gate

Gitea treats github.* as an alias for gitea.*. The pattern was canaried
in this form, and pr-flow only detects a gate written this way.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.gitea/workflows/firefox-extension.yml

@@ -10,10 +10,12 @@ on:
       - main
   workflow_dispatch:
 
+# The gate and concurrency use the github.* context, Gitea's alias for gitea.*:
+# it is the form the pattern was canaried with and the one pr-flow detects.
 concurrency:
-  group: ${{ gitea.workflow }}-${{ gitea.ref }}
+  group: ${{ github.workflow }}-${{ github.ref }}
   # Cancel superseded PR runs, never a push run: main's push uploads the package.
-  cancel-in-progress: ${{ gitea.event_name == 'pull_request' }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
 
 jobs:
   validate:
@@ -21,9 +23,9 @@ jobs:
     # the title and nothing else, since a skipped job reports success on the
     # required check (see ~/.claude/docs/gitea-ci-pattern.md).
     if: >-
-      gitea.event_name != 'pull_request' || (
+      github.event_name != 'pull_request' || (
-        !startsWith(gitea.event.pull_request.title, 'WIP:') &&
+        !startsWith(github.event.pull_request.title, 'WIP:') &&
-        !startsWith(gitea.event.pull_request.title, '[WIP]')
+        !startsWith(github.event.pull_request.title, '[WIP]')
       )
     runs-on: ubuntu-latest
     steps: