scuffle-bootstrap: test coverage and docs

[lennartkloock]

• Add test coverage
• Add docs

Closes CLOUD-5

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 53.46%. Comparing base (87971c7) to head (343d642).

❗ Current head 343d642 differs from pull request most recent head f252ff8

Please upload reports for the commit f252ff8 to get more accurate results.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #240      +/-   ##
==========================================
+ Coverage   50.43%   53.46%   +3.02%     
==========================================
  Files         198      198              
  Lines       16269    16266       -3     
==========================================
+ Hits         8206     8696     +490     
+ Misses       8063     7570     -493     

Files with missing lines	Coverage Δ
crates/bootstrap/src/config.rs	100.00% <ø> (+100.00%)	⬆️
crates/bootstrap/src/global.rs	92.43% <100.00%> (+92.43%)	⬆️
crates/bootstrap/src/service.rs	100.00% <ø> (+100.00%)	⬆️

... and 3 files with indirect coverage changes

Components	Coverage Δ
scuffle-batching	100.00% <ø> (ø)
scuffle-bootstrap	52.54% <100.00%> (+25.39%)	⬆️
scuffle-context	100.00% <ø> (ø)
scuffle-ffmpeg	0.00% <ø> (ø)
scuffle-h3-webtransport	0.00% <ø> (ø)
scuffle-http	0.00% <ø> (ø)
scuffle-metrics	42.69% <ø> (ø)
scuffle-pprof	0.00% <ø> (ø)
scuffle-settings	0.00% <ø> (ø)
scuffle-signal	100.00% <ø> (ø)
postcompile	77.32% <ø> (+77.32%)	⬆️
scuffle-image-processor	∅ <ø> (∅)