Add Avocado Zero (Games) catalog manifest

[Endika]

Application Submission

• Added Avocado Zero (flipper_avocado_zero), a small care-sim game for Flipper Zero.
• Main gameplay loop:
  • Keep the avocado pit alive by cleaning dirty water.
  • Time progression increases dirtiness while away.
  • Root growth progresses when the pit is well maintained.
  • Win condition when roots reach full growth; lose condition if water becomes too poor.
• Included app metadata updates for catalog submission:
  • Complete manifest fields (name, author, version, category, descriptions, changelog, screenshots).
  • Repository + pinned commit_sha for reproducible builds.

Extra Requirements

• No extra hardware required.
• No extra software required beyond standard Flipper Zero external app support (built with ufbt).

Author Checklist (Fill this out)

• I've read the contribution guidelines and my PR follows them
• I own the code I'm submitting or have code owner's permission to submit it
• I have validated the manifest file(s) with python3 tools/bundle.py --nolint applications/CATEGORY/APPID/manifest.yml bundle.zip

Reviewer Checklist (Don't fill this out)

• Bundle is valid
• There are no obvious issues with the source code
• I've ran this application and verified its functionality