Removed Transport mock

[pompon0]

We have 1 transport implementation and it should be used everywhere instead of being mocked out.
Removed the "memory" addressing and "Protocol" altogether. Only TCP addresses are valid now.

[github-actions]

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Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	Oct 1, 2025, 2:50 PM

[codecov]

Codecov Report

❌ Patch coverage is 85.26316% with 28 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.86%. Comparing base (3f7dfae) to head (acba1c9).
⚠️ Report is 2 commits behind head on gprusak-reapply.

Files with missing lines	Patch %	Lines
internal/p2p/transport.go	84.09%	20 Missing and 8 partials ⚠️

Additional details and impacted files

@@                 Coverage Diff                 @@
##           gprusak-reapply     #328      +/-   ##
===================================================
- Coverage            56.88%   56.86%   -0.02%     
===================================================
  Files                  255      254       -1     
  Lines                33830    33734      -96     
===================================================
- Hits                 19245    19184      -61     
+ Misses               13049    13019      -30     
+ Partials              1536     1531       -5     

Files with missing lines	Coverage Δ
internal/p2p/address.go	89.55% <100.00%> (-5.87%)	⬇️
internal/p2p/router.go	75.10% <100.00%> (-0.65%)	⬇️
node/setup.go	69.38% <100.00%> (ø)
internal/p2p/transport.go	84.15% <84.09%> (+13.42%)	⬆️

... and 6 files with indirect coverage changes

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