chore: move Shelly setup scripts to pyro-sys-setup

[MateoLostanlen]

• pyro-engine keeps only watchdog.js, the script that runs on the Shelly. Setup and hardening scripts now live in pyro-sys-setup.
• Drop update_shelly_watchdog.sh: setup_shelly_watchdog.sh already updates an existing script.
• Merge after feat: provision and harden Shelly watchdogs without the phone app pyro-sys-setup#37.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.46%. Comparing base (48ad5f1) to head (6527e19).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #450   +/-   ##
========================================
  Coverage    79.46%   79.46%           
========================================
  Files            6        6           
  Lines          852      852           
========================================
  Hits           677      677           
  Misses         175      175           

Flag	Coverage Δ
unittests	79.46% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.