refactor(csharp): cleanup tcp connection after vsr implementation

[lukaszzborek]

Follow-up cleanup of the .NET SDK TCP transport after the VSR support landed

[codecov]

Codecov Report

❌ Patch coverage is 83.29571% with 74 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.15%. Comparing base (e71e3c6) to head (eb05031).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
foreign/csharp/Iggy_SDK/Vsr/VsrConnection.cs	82.22%	26 Missing and 6 partials ⚠️
...IggyClient/Implementations/TcpMessageStream.Vsr.cs	71.01%	14 Missing and 6 partials ⚠️
...SDK/IggyClient/Implementations/TcpMessageStream.cs	92.06%	6 Missing and 4 partials ⚠️
foreign/csharp/Iggy_SDK/Consumers/IggyConsumer.cs	85.10%	2 Missing and 5 partials ⚠️
foreign/csharp/Iggy_SDK/Utils/ArrayPoolHelper.cs	75.00%	2 Missing and 1 partial ⚠️
...n/csharp/Iggy_SDK/Consumers/IggyConsumer.Rented.cs	0.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #3858      +/-   ##
============================================
- Coverage     83.67%   83.15%   -0.52%     
+ Complexity     1358     1340      -18     
============================================
  Files          1212     1220       +8     
  Lines        165138   164377     -761     
  Branches     132612   132688      +76     
============================================
- Hits         138181   136695    -1486     
- Misses        23308    23928     +620     
- Partials       3649     3754     +105     

Components	Coverage Δ
Rust Core	83.81% <ø> (-0.63%)	⬇️
Java SDK	66.54% <ø> (-0.13%)	⬇️
C# SDK	74.96% <83.21%> (-1.12%)	⬇️
Python SDK	90.00% <ø> (ø)
PHP SDK	84.48% <ø> (ø)
Node SDK	95.82% <ø> (-0.02%)	⬇️
Go SDK	69.04% <ø> (+0.72%)	⬆️

Files with missing lines	Coverage Δ
foreign/csharp/Iggy_SDK/Mappers/BinaryMapper.cs	90.40% <100.00%> (-1.79%)	⬇️
...n/csharp/Iggy_SDK/Utils/TcpMessageStreamHelpers.cs	94.28% <ø> (+9.50%)	⬆️
foreign/csharp/Iggy_SDK/Vsr/ConsensusSession.cs	99.00% <100.00%> (-1.00%)	⬇️
...n/csharp/Iggy_SDK/Consumers/IggyConsumer.Rented.cs	68.69% <0.00%> (-4.99%)	⬇️
foreign/csharp/Iggy_SDK/Utils/ArrayPoolHelper.cs	75.00% <75.00%> (ø)
foreign/csharp/Iggy_SDK/Consumers/IggyConsumer.cs	73.57% <85.10%> (+7.89%)	⬆️
...SDK/IggyClient/Implementations/TcpMessageStream.cs	79.05% <92.06%> (-1.87%)	⬇️
...IggyClient/Implementations/TcpMessageStream.Vsr.cs	72.72% <71.01%> (+0.82%)	⬆️
foreign/csharp/Iggy_SDK/Vsr/VsrConnection.cs	82.22% <82.22%> (ø)

... and 161 files with indirect coverage changes

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[lukaszzborek]

If possible, merge #3836 first. Then I will remove things with namespace which I refactoring 😅

[hubcio]

solid direction overall - classic framing gone, the VsrConnection extraction, typed namespaces and the epoch rejoin are real improvements. blocking items are the probe losing its reconnect, the never-nulled _connection, the fail-open namespace and the edge-based Disconnected clear; the rest is small.

one thing outside the diff: SetConnectionStateAsync (TcpMessageStream.cs:1153) is a non-atomic check-then-set with the publish after the write, reachable from callers holding different locks - concurrent transitions can publish duplicates or a PreviousState that never actually preceded CurrentState. it predates this PR, and fixing it properly means moving the publish behind an ordered queue (holding a lock across the publish is not an option - the handler chain runs synchronously into socket I/O when the semaphores are uncontended, so a sync write fault re-enters the same lock). follow-up material, but it is the substrate under the Disconnected-clear race flagged inline.

[lukaszzborek]

/ready