chore: remove tools.go in favor of go.mod tool directive

[phm07]

Continued from #559

Since Go 1.24 is now 2 major versions old, we can use the new tool directive in go.mod instead of a dedicated tools.go file.
Unfortunately this does not resolve the dependency problem, since the tools' dependencies are still pulled into go.mod.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.39%. Comparing base (b5d4aa6) to head (faec47c).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #847   +/-   ##
=======================================
  Coverage   78.39%   78.39%           
=======================================
  Files          60       60           
  Lines        4355     4355           
=======================================
  Hits         3414     3414           
  Misses        637      637           
  Partials      304      304           

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