A PR that only touches `uv.lock` currently gets the label of its' dir
because the file rule matches on the file prefix. This is misleading —
lockfile-only changes aren't meaningful package changes. The
`excludedFiles` list already existed in config (for size calculations),
but file rules didn't consult it.
## Changes
- Add `skipExcludedFiles` option to file rules in
`pr-labeler-config.json`, enabled for the four package rules
(`deepagents`, `cli`, `acp`, `evals`) so lockfile-only PRs don't trigger
package labels
- `matchFileLabels` in `pr-labeler.js` now filters out files whose
basename appears in the top-level `excludedFiles` list (currently just
`uv.lock`) before testing rules that opt in via `skipExcluded`
- Non-package rules (`github_actions`, `dependencies`) are unaffected —
they don't set the flag
`pr-labeler.js` used `require('@actions/core')` to access GitHub Actions
logging/failure helpers, but that module is bundled inside
`actions/github-script`'s dist — it's not resolvable via Node's
`require()` from a checked-out file on disk. Two of the three call sites
were in rarely-hit error branches, so the bug was latent. The third
(`applyTierLabel`) ran unconditionally, crashing the tier-label step on
every external PR. Because the tier step runs *before* the "add external
label" step, the crash prevented the `external` label from ever being
applied — which meant `require_issue_link.yml` never triggered and
unapproved external PRs stayed open.
## Changes
- Thread the `core` object (provided by `actions/github-script` at eval
time) through `loadAndInit()` → `init()` instead of calling
`require('@actions/core')` from the checked-out script — fixes the
`MODULE_NOT_FOUND` crash on all three call sites (`ensureLabel`,
`getContributorInfo`, `applyTierLabel`)
- Add a console-based fallback in `loadAndInit` so callers that don't
need `core.setFailed` still work without passing it
- Update all 9 `loadAndInit(github, owner, repo)` call sites across
`pr_labeler.yml`, `pr_labeler_backfill.yml`, and
`tag-external-issues.yml` to pass `core`
Consolidate four separate PR labeling workflows (`pr_labeler_file.yml`,
`pr_labeler_title.yml`, `pr_size_labeler.yml`, and the PR-handling half
of `tag-external-contributions.yml`) into a single `pr_labeler.yml`
workflow. The old workflows raced against each other — concurrent label
mutations could drop or duplicate labels depending on execution order. A
unified workflow with concurrency grouping eliminates that class of bug.
