refactor: improve conversation list rendering performance

[MohamadJaara]

Refactors conversation list item rendering to avoid doing UI-only and expensive work during paged item mapping. Search highlighting, legal-hold visibility, and currently playing audio state are now applied closer to rendering, reducing unnecessary remapping when those UI states change.

Also defers last-message markdown preview parsing to the UI layer and adds a lightweight markdown preview parser so conversation subtitles avoid full markdown parsing while preserving formatted previews.

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
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 55.91398% with 41 lines in your changes missing coverage. Please review.
✅ Project coverage is 51.19%. Comparing base (9341b52) to head (47174d4).

Files with missing lines	Patch %	Lines
...id/ui/markdown/LightweightMarkdownPreviewParser.kt	53.33%	6 Missing and 8 partials ⚠️
...ome/conversationslist/ConversationListViewModel.kt	44.44%	10 Missing ⚠️
...tions/usecase/GetConversationsFromSearchUseCase.kt	62.50%	4 Missing and 2 partials ⚠️
...i/home/conversationslist/model/ConversationItem.kt	33.33%	4 Missing ⚠️
...tlin/com/wire/android/mapper/ConversationMapper.kt	66.66%	2 Missing and 1 partial ⚠️
...wire/android/mapper/MessagePreviewContentMapper.kt	75.00%	2 Missing ⚠️
...lin/com/wire/android/ui/markdown/MarkdownParser.kt	66.66%	0 Missing and 2 partials ⚠️

❌ Your patch check has failed because the patch coverage (55.91%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #4853      +/-   ##
===========================================
- Coverage    51.26%   51.19%   -0.08%     
===========================================
  Files          611      612       +1     
  Lines        21181    21172       -9     
  Branches      3405     3421      +16     
===========================================
- Hits         10859    10839      -20     
- Misses        9308     9318      +10     
- Partials      1014     1015       +1     

Files with missing lines	Coverage Δ
...wire/android/mapper/MessagePreviewContentMapper.kt	58.87% <75.00%> (+0.30%)	⬆️
...lin/com/wire/android/ui/markdown/MarkdownParser.kt	67.50% <66.66%> (-0.07%)	⬇️
...tlin/com/wire/android/mapper/ConversationMapper.kt	54.16% <66.66%> (+1.18%)	⬆️
...i/home/conversationslist/model/ConversationItem.kt	54.86% <33.33%> (-1.50%)	⬇️
...tions/usecase/GetConversationsFromSearchUseCase.kt	74.24% <62.50%> (-6.80%)	⬇️
...ome/conversationslist/ConversationListViewModel.kt	29.29% <44.44%> (-5.79%)	⬇️
...id/ui/markdown/LightweightMarkdownPreviewParser.kt	53.33% <53.33%> (ø)

... and 3 files with indirect coverage changes

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[saleniuk]

I think that conversationItem.searchQuery and conversationItem.playingAudio are not being set anywhere anymore, apart from some mocks and previews, so to avoid the confusion as to whether these fields in the ConversationItem are filled in and correct or not, maybe we should decide to only provide them externally like here and remove these fields completely from ConversationItem?
About legal hold field, maybe we could simplify it to make ConversationItem to have LegalHoldStatus field instead and move the logic of determining showLegalHoldIndicator completely to ConversationItemFactory as now it's scattered around and some part is determined in ConversationMapper, then in ConversationListViewModel and finally in ConversationItemFactory 🤔