auto-log: fetch failing-job log from Gitea API into the details block

New optional inputs (all default to off / safe):
  - auto-log: when true and details is empty, fetch and render the run's
    failing-job log via /api/v1/repos/<repo>/actions/jobs/<id>/logs.
  - token: defaults to github.token (per-run, repo-scoped). Overridable.
  - log-lines: tail-length fallback when no ::error:: annotation present.

Selection heuristic: if any line has ::error::, return those + 12 lines of
context above each (merged windows). Otherwise the last `log-lines` lines.
Timestamp prefixes (act_runner's leading ISO-8601 + Z) are stripped.

The details block already existed; this just makes it cheap for failure
emails to surface the actual build error inline instead of forcing the
reader to click "view run →".

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

action.yaml

@@ -28,6 +28,24 @@ inputs:
     description: Optional multiline preformatted block (rendered in a monospace card). Leave empty to omit.
     required: false
     default: ''
+  auto-log:
+    description: |
+      If 'true' AND details is empty, fetch the current run's failing-job log via the
+      Gitea API and render the relevant tail as the details block. Useful for failure
+      notifications so the email shows the actual error inline. Requires `token`.
+    required: false
+    default: 'false'
+  token:
+    description: |
+      Gitea API token used to fetch the run log when `auto-log: true`. Defaults to
+      the run's per-job GITHUB_TOKEN which has read access to the current repo's
+      actions. Pass `${{ secrets.CI_BOT_TOKEN }}` only if GITHUB_TOKEN isn't enough.
+    required: false
+    default: ${{ github.token }}
+  log-lines:
+    description: How many tail lines of the failing step to include when no `::error::` annotation is found.
+    required: false
+    default: '40'
   smtp-host:
     description: SMTP relay host.
     required: false
@@ -48,6 +66,9 @@ runs:
         NOTIFY_SUBJECT: ${{ inputs.subject }}
         NOTIFY_SUMMARY: ${{ inputs.summary }}
         NOTIFY_DETAILS: ${{ inputs.details }}
+        NOTIFY_AUTO_LOG: ${{ inputs.auto-log }}
+        NOTIFY_TOKEN: ${{ inputs.token }}
+        NOTIFY_LOG_LINES: ${{ inputs.log-lines }}
         NOTIFY_SMTP_HOST: ${{ inputs.smtp-host }}
         NOTIFY_SMTP_PORT: ${{ inputs.smtp-port }}
         GH_SERVER_URL: ${{ github.server_url }}