Add ANNOUNCE_RULES for sample media tracks

[paulpv]

We need to document ANNOUNCE_RULES metadata for the sample audio assets shipped in media/ so they can be referenced consistently during testing and demos.

Tracks missing entries:

• media/Alex-Productions/Soundtrack – Epic Cinematic Background Music ｜ Alex-Productions [QVeiLLbKx2g].mp3
• media/Pedro Macedo Camacho/Star Citizen： ＂Day in Paradise＂ [aAiQWNZ6HF4].mp3
• media/Scott Buckley/Discovery – Scott Buckley (No Copyright Music) [M8ZwIybVy3o].mp3

Please add ANNOUNCE_RULES coverage for these files (or clarify how they should be surfaced if a different pattern is expected). Update any relevant docs if the workflow changes.