fix(gap): allow empty service and manufacturer data payloads

[bdraco]

Fixes #179 - Advertisement parsing now correctly handles service data and manufacturer data with empty payloads (UUID/company ID only).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (c65b433) to head (b79548a).
⚠️ Report is 12 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #180   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            6         6           
  Lines          255       255           
  Branches        38        38           
=========================================
  Hits           255       255           

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[codspeed-hq]

CodSpeed Performance Report

Merging #180 will not alter performance

_{Comparing allow_empty_service_mfr_data (b79548a) with main (c65b433)}

Summary

✅ 9 untouched