ux: clarify reporter delivery logs

[favonia]

Make successful Shoutrrr logs identify the notification type, and shorten Healthchecks success logs from Successfully sent ... to Sent .... Notification metadata is assigned at the command and updater boundaries, leaving remote payloads, delivery and error behavior, and quiet output unchanged. Closes #959.

[codecov]

Codecov Report

❌ Patch coverage is 94.18605% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 98.59%. Comparing base (3dab253) to head (19aabcf).

Files with missing lines	Patch %	Lines
cmd/ddns/ddns.go	28.57%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1250      +/-   ##
==========================================
+ Coverage   98.49%   98.59%   +0.09%     
==========================================
  Files         100      102       +2     
  Lines        6255     6319      +64     
==========================================
+ Hits         6161     6230      +69     
+ Misses         81       76       -5     
  Partials       13       13              

Flag	Coverage Δ
smoketests	11.84% <10.46%> (-0.03%)	⬇️
unittests	98.22% <93.02%> (+0.11%)	⬆️

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