fix(moq): fail connection on audio codec mismatch in pull node

[staging-devin-ai-integration]

Summary

When catalog discovery during initialize() fails or times out, the MoQ pull node keeps the constructor's default output pin type (Opus). If run_connection() later discovers a different catalog audio codec, it previously only logged a warning but continued sending packets with the mismatched codec — a pin contract violation.

This PR makes run_connection() return Err(StreamKitError::Runtime(...)) on codec mismatch, which causes the reconnection loop (line 197) to retry, giving catalog discovery another chance.

Changes:

• After the existing tracing::warn! in the mismatch block (~line 687), return an error to fail the connection
• Replace the trivial test_codec_mismatch_detectable test (which only asserted Opus != Aac) with four focused tests:
  • test_default_node_has_opus_output_pin — default config produces Opus pin
  • test_codec_mismatch_detected_between_pin_and_catalog — mismatch scenario (Opus pin vs AAC catalog)
  • test_no_mismatch_when_pin_matches_catalog — matching codecs don't trigger failure
  • test_explicit_aac_config_avoids_mismatch_with_aac_catalog — explicit AAC config avoids mismatch

Closes #454

Review & Testing Checklist for Human

• Verify that the error message in run_connection() is clear and actionable in logs
• Confirm that the reconnection loop at line 197 handles this error the same as other StreamKitError::Runtime errors (1s retry)
• Test with a real MoQ broadcast where catalog discovery initially times out but succeeds on retry — verify the node recovers

Notes

This is the safer of the two options from the issue — failing the connection rather than updating pin types at runtime. Runtime pin updates can be done as a follow-up if needed.

Link to Devin session: https://staging.itsdev.in/sessions/8ccfbaefee4d496ab9e2b402efabf989
Requested by: @streamer45

[staging-devin-ai-integration]

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[codecov]

Codecov Report

❌ Patch coverage is 77.77778% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 65.93%. Comparing base (bddff06) to head (3a344b3).

Files with missing lines	Patch %	Lines
crates/nodes/src/transport/moq/pull.rs	77.77%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #461      +/-   ##
==========================================
+ Coverage   65.91%   65.93%   +0.02%     
==========================================
  Files         217      217              
  Lines       57496    57530      +34     
  Branches     1597     1597              
==========================================
+ Hits        37896    37931      +35     
+ Misses      19594    19593       -1     
  Partials        6        6              

Flag	Coverage Δ
backend	65.01% <77.77%> (+0.02%)	⬆️

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

Components	Coverage Δ
core	84.29% <ø> (ø)
engine	75.57% <ø> (ø)
api	84.73% <ø> (ø)
nodes	67.46% <77.77%> (+0.06%)	⬆️
server	57.16% <ø> (-0.02%)	⬇️
plugin-native	70.93% <ø> (ø)
plugin-wasm	6.37% <ø> (ø)
ui-services	74.73% <ø> (ø)
ui-components	60.49% <ø> (ø)

Files with missing lines	Coverage Δ
crates/nodes/src/transport/moq/pull.rs	35.01% <77.77%> (+1.86%)	⬆️

... and 2 files with indirect coverage changes

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