Improve MLS epoch mismatch recovery observability [WPB-21916]

[thisisamir98]

WPB-21916 [Web/Desktop] : Missing messages in Web - Prod

Add structured logging across the MLS recovery path so Datadog can correlate why clients end up in external-commit rejoin and show the "conversation recovered" system message.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

❌ Patch coverage is 87.17949% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 45.74%. Comparing base (50f602e) to head (403f5ab).
⚠️ Report is 1 commits behind head on dev.

Files with missing lines	Patch %	Lines
...rsation/conversationService/conversationService.ts	90.62%	2 Missing and 1 partial ⚠️
...epositories/conversation/ConversationRepository.ts	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev   #21382      +/-   ##
==========================================
+ Coverage   45.72%   45.74%   +0.01%     
==========================================
  Files        1696     1696              
  Lines       43668    43685      +17     
  Branches     9095     9094       -1     
==========================================
+ Hits        19968    19982      +14     
- Misses      21439    21442       +3     
  Partials     2261     2261              

Flag	Coverage Δ
app_webapp	43.92% <0.00%> (-0.01%)	⬇️
lib_api_client	51.74% <ø> (ø)
lib_core	59.05% <91.89%> (+0.14%)	⬆️

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

Files with missing lines	Coverage Δ
.../core/src/messagingProtocols/mls/recovery/index.ts	100.00% <ø> (ø)
...gProtocols/mls/recovery/mlsRecoveryOrchestrator.ts	83.50% <100.00%> (+0.70%)	⬆️
...epositories/conversation/ConversationRepository.ts	46.53% <0.00%> (-0.06%)	⬇️
...rsation/conversationService/conversationService.ts	65.92% <90.62%> (+0.90%)	⬆️

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[github-actions]

🔗 Download Full Report Artifact

🧪 Playwright Test Summary

• ✅ Passed: 15
• ❌ Failed: 0
• ⏭ Skipped: 0
• 🔁 Flaky: 0
• 📊 Total: 15
• ⏱ Total Runtime: 158.3s (~ 2 min 38 sec)