SIDpulse Tracker v0.2.17

SIDpulse Tracker v0.2.17

Startup splash correction

The startup splash now presents the two actual choices:

• New song creates a blank Untitled project.
• Play demo song keeps the bundled editable Autumn at five project and
  starts playback as before.

Escape follows New song. This fixes v0.2.16 behavior where dismissing the
splash without playing still left the demo song loaded in the editor.

The Don't show this on startup preference is unchanged. Explicit
--play-welcome-song playback is unchanged, as are audio startup behavior,
project format 6, dependency pins and export semantics.

Compatibility and limits

This is a focused UI/startup bug-fix release over v0.2.16. No song-format,
sequencer, SID-player, audio-buffer or dependency changes are introduced.

Download sidpulse-tracker-v0.2.17-full.zip and
sidpulse-tracker-v0.2.17-SHA256SUMS.txt. Verify the checksum, then follow the
README. The release-validation procedure is recorded in docs/VALIDATION.md.