fix: run the app-ci path filter on pull requests only (#1)

dorny/paths-filter uses the GitHub API on a pull_request event, but on a
push it has to diff against github.event.before with git. That commit is
not in the changes job's default depth-1 checkout, so it fetches it — and
the checkout persists no credential (zizmor requires that), so on a
private repository the fetch dies with "could not read Username for
'https://github.com'". Every push to main after the first one therefore
failed the changes job, which skipped ci and commitlint: the merge gate
existed on pull requests only. The first push to a branch survived just
because github.event.before is the all-zero sha there.

Gate build-filters and the filter on github.event_name == 'pull_request'
and fall the job's roots output back to inputs.roots otherwise. The
filter is a pull-request time saver — most roots are untouched there —
while on the default branch every root should be verified anyway, so the
non-pull-request branch wants the full list regardless. Both branches
emit a JSON array string, so fromJSON and the ci job's != '[]' guard keep
working, no fetch-depth change is needed, and persist-credentials: false
stays.

Claude-Session: https://claude.ai/code/session_01J4HB8qJjdZwaAv42k6HMpv

Co-authored-by: iam-truongtrungnghia <nghia.truong@tpssoft.com>

Author: ttncode

.github/workflows/app-ci.yml

@@ -16,12 +16,22 @@ jobs:
       contents: read
       pull-requests: read
     outputs:
-      roots: ${{ steps.filter.outputs.changes }}
+      # the filter only runs on a pull request, so on every other event this
+      # falls back to the full input: a push to the default branch is exactly
+      # where every root should be verified, not a subset. that also keeps
+      # paths-filter away from `git`, which it needs on a push (it diffs
+      # against github.event.before, a commit a depth-1 checkout does not
+      # have) and cannot use, because the checkout persists no credential
+      # for it to fetch that commit with on a private repository.
+      roots: ${{ steps.filter.outputs.changes || inputs.roots }}
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           persist-credentials: false
-      - id: build-filters
+      # the filter is a pull-request time saver: most roots are untouched
+      # there. on any other event the job outputs inputs.roots unchanged.
+      - if: github.event_name == 'pull_request'
+        id: build-filters
         env:
           ROOTS: ${{ inputs.roots }}
         # a root is dirty when its own directory, a lockfile, or the root
@@ -30,7 +40,8 @@ jobs:
           echo "$ROOTS" \
             | jq -r '.[] | "\(.):\n  - \(.)/**\n  - mise.toml\n  - \"*.lock*\""' \
             > "${RUNNER_TEMP}/filters.yml"
-      - id: filter
+      - if: github.event_name == 'pull_request'
+        id: filter
         uses: dorny/paths-filter@ceb8a2b8f2d89434be7ff52d3de7ec3738c5cc9d # v4.0.3
         with:
           filters: ${{ runner.temp }}/filters.yml