Rollforward "refactor of MConnection internals"

[pompon0]

rollforward of #324
Fixed bug detected by #327. Fix is here d23a7aa

[github-actions]

The latest Buf updates on your PR. Results from workflow Buf / buf (pull_request).

Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	Oct 1, 2025, 2:01 PM

[codecov]

Codecov Report

❌ Patch coverage is 66.56805% with 113 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.96%. Comparing base (c6c5a8f) to head (8ae4f9f).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/p2p/conn/connection.go	86.45%	27 Missing and 7 partials ⚠️
libs/utils/ringbuf.go	0.00%	34 Missing ⚠️
libs/utils/scope/global.go	0.00%	30 Missing ⚠️
libs/utils/wait.go	0.00%	8 Missing ⚠️
libs/utils/proto.go	0.00%	7 Missing ⚠️

❌ Your patch status has failed because the patch coverage (66.56%) is below the target coverage (70.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #326      +/-   ##
==========================================
+ Coverage   56.94%   56.96%   +0.01%     
==========================================
  Files         254      255       +1     
  Lines       33815    33830      +15     
==========================================
+ Hits        19257    19271      +14     
- Misses      13017    13028      +11     
+ Partials     1541     1531      -10     

Files with missing lines	Coverage Δ
internal/p2p/router.go	78.96% <100.00%> (+3.42%)	⬆️
libs/utils/proto.go	1.61% <0.00%> (-0.21%)	⬇️
libs/utils/wait.go	8.21% <0.00%> (-1.02%)	⬇️
libs/utils/scope/global.go	0.00% <0.00%> (ø)
internal/p2p/conn/connection.go	84.06% <86.45%> (+5.37%)	⬆️
libs/utils/ringbuf.go	0.00% <0.00%> (ø)

... and 6 files with indirect coverage changes

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