feat(consensus): add loopback queue for primary self-addressed messages

[hubcio]

The primary was sending PrepareOk to itself through the message
bus, requiring a network round-trip and an unwrap() on bus
errors. Replace with an in-process VecDeque that the simulator
drains after each dispatch. Cleared on view change reset and
on DVC quorum completion.

Includes defensive debug_assert guards on push_loopback
overflow, process_loopback buf precondition, and simulator
drain idempotency. Adds test verifying loopback is cleared
when complete_view_change_as_primary fires.

[codecov]

Codecov Report

❌ Patch coverage is 76.82119% with 35 lines in your changes missing coverage. Please review.
✅ Project coverage is 67.88%. Comparing base (2eefbc3) to head (fbda38a).

Files with missing lines	Patch %	Lines
core/shard/src/lib.rs	0.00%	30 Missing ⚠️
core/simulator/src/lib.rs	0.00%	4 Missing ⚠️
core/consensus/src/impls.rs	92.30%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #2825      +/-   ##
============================================
+ Coverage     67.53%   67.88%   +0.35%     
  Complexity      739      739              
============================================
  Files          1048     1048              
  Lines         84103    84247     +144     
  Branches      60704    60857     +153     
============================================
+ Hits          56795    57195     +400     
+ Misses        24950    24678     -272     
- Partials       2358     2374      +16     

Flag	Coverage Δ
csharp	67.06% <ø> (-0.19%)	⬇️
go	6.33% <ø> (ø)
java	54.83% <ø> (ø)
node	92.18% <ø> (-0.15%)	⬇️
python	0.00% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
core/consensus/src/plane_helpers.rs	56.57% <100.00%> (+36.01%)	⬆️
core/consensus/src/impls.rs	41.52% <92.30%> (+26.13%)	⬆️
core/simulator/src/lib.rs	0.00% <0.00%> (ø)
core/shard/src/lib.rs	0.00% <0.00%> (ø)

... and 19 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[numinnex]

We don't send only PrepareOk to our selves, other messages such as DoViewChange and StartViewChange.

[numinnex]

Also use that method inside of the send_message_to_replica or however it's called method, when the replica_id == self.replica_id.