perf: replace tokio full features with explicit list

[bug-ops]

Summary

• Replace tokio = { features = ["full"] } with ["macros", "rt-multi-thread", "signal", "sync"] in root binary
• Avoids compiling unused tokio features (io-util, fs, parking_lot, test-util, etc.)
• Expected 10-15% tokio compile time reduction on clean builds

Closes #314

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@            Coverage Diff             @@
##             main     #326      +/-   ##
==========================================
+ Coverage   79.96%   80.29%   +0.33%     
==========================================
  Files          98       99       +1     
  Lines       23964    23900      -64     
==========================================
+ Hits        19163    19191      +28     
+ Misses       4801     4709      -92     

see 8 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.