fix(ci): remove hardcoded DISPLAY=:99 (#324)

* fix(ci): remove xvfb-action from self-hosted runner

The self-hosted runner has a live KDE Plasma session with real display.
Xvfb is unnecessary and the action also uses apt-get internally which
doesn't exist on Fedora/Nobara.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* fix(ci): remove hardcoded DISPLAY=:99, use live session

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

---------

Co-authored-by: Coldaine <coldaine@example.com>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: 3 people

.github/workflows/ci.yml

@@ -232,7 +232,7 @@ jobs:
     needs: [setup-whisper-dependencies]
     timeout-minutes: 30
     env:
-      DISPLAY: :99
+      # DISPLAY inherited from runner's live KDE session (do NOT hardcode :99)
       RUST_LOG: debug
       RUST_TEST_TIME_UNIT: 10000
       RUST_TEST_TIME_INTEGRATION: 30000