Add aprstx manifest

[yo3gnd]

Application Submission

• Flipper ham APRS TX is an experimental APRS / AX.25 transmitter for Flipper Zero. It does not use the Flipper as an audio source for another radio; it drives the Sub-GHz hardware directly and produces something APRS-like using only the device itself. The app can send APRS messages, status packets, bulletins, and fixed-position packets. It also keeps a small destination callbook, remembers settings, and exposes a few RF-side controls for coaxing receivers into decoding it. This is its first submission to the catalog.

Extra Requirements

• No extra hardware is required to run the app itself. To receive or decode packets, you will need something listening on a suitable frequency, such as a handheld, SDR, software decoder or gateway such as Direwolf. The app is still experimental, receiver-dependent, and subject to the usual legal restrictions on transmission in the relevant bands.

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