fix: reset S400 stabilized on idle packet and add stabilized support for Scale v1/v2

[dckiller51]

Summary

Follow-up to the merged PR adding stabilized binary sensor for S400. This PR fixes a bug where the S400 stabilized sensor was not reset when the user stepped off the scale, and extends stabilized support to Mi Smart Scale v1 and Mi Body Composition Scale v2.

Changes

_parse_xiaomi — S400 idle packet fix

• Added _S400_MODELS class attribute (MJTZC01YM, MJTZC03YM)
• When an S400 idle packet is received (frctrl_object_include == 0), the stabilized sensor is now reset to OFF — previously it was silently ignored, leaving the sensor stuck on ON after a barefoot weighing

_parse_scale_v1 — Mi Smart Scale (XMTZC01HM/XMTZC04HM)

• Added stabilized binary sensor: ON when mass_stabilized=True and mass > 0, OFF otherwise
• Reset to OFF on mass == 0 (person stepped off)

_parse_scale_v2 — Mi Body Composition Scale (XMTZC02HM/XMTZC05HM/NUN4049CN)

• Added stabilized binary sensor with the same logic as v1
• Impedance is only published when impedance_stabilized=True

Tests added

• test_Xiaomi_Scale1_reset — v1 reset when person steps off (mass=0, stabilized=False)
• test_Xiaomi_Scale2_reset — v2 reset when person steps off (mass=0, stabilized=False)

[codecov]

Codecov Report

❌ Patch coverage is 87.50000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 55.19%. Comparing base (a5f55ec) to head (3c2859b).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/xiaomi_ble/parser.py	86.66%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #322      +/-   ##
==========================================
+ Coverage   54.91%   55.19%   +0.27%     
==========================================
  Files           7        7              
  Lines        1393     1406      +13     
  Branches      271      276       +5     
==========================================
+ Hits          765      776      +11     
- Misses        513      514       +1     
- Partials      115      116       +1     

☔ 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.

[dckiller51]

@Ernst79 Great, thank you! As soon as you merge these changes, I'll handle the next step and open a PR to add these modifications to Home Assistant's native xiaomi_ble component.

[Ernst79]

LGTM thanks