Add moisture sensor reader app

[smallwat3r]

Application Submission

A Flipper Zero application that reads values from a Capacitive Moisture Sensor v1.2.

• Real-time moisture percentage display (0-100%)
• Visual moisture bar indicator
• Status text (Very Dry, Dry, Moist, Wet, Very Wet)
• Millivolt and raw ADC value display
• Averaged readings for stability
• In-app calibration menu with persistent storage

Extra Requirements

• Capacitive Moisture Sensor v1.2 (link)

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