fix: move message asset paths to conversation-scoped cache VM [WPB-25002]

[Garzas]

https://wearezeta.atlassian.net/browse/WPB-25002

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• The PR Title

  • conforms to the style of semantic commits messages¹ supported in Wire's Github Workflow²
  • contains a reference JIRA issue number like SQPIT-764
  • answers the question: If merged, this PR will: ... ³

• The PR Description

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What's new in this PR?

Issues

• Single-asset messages could get stuck in loading/downloading when switching conversations quickly.
• Local asset paths were being lost because state was tied to short-lived per-item lifecycle.
• Loading overlays could still appear even when a valid local image source existed.

Causes (Optional)

• Asset path state was stored per item, so detach/reattach could recreate state with null path.
• UI loading decisions relied too much on transfer status instead of source availability.

Solutions

• Moved message-list asset path handling to a conversation-scoped cache ViewModel (messageId -> localPath) and updated image/video/asset rendering to use it.
• Updated image overlay/render logic to prioritize available local sources and prevent unnecessary loading placeholders.
• Added unit tests for the new conversation-scoped asset path flow, including regression coverage for in-progress transfer scenarios.

[codecov]

Codecov Report

❌ Patch coverage is 55.00000% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 50.80%. Comparing base (67d21d4) to head (16becde).
⚠️ Report is 1 commits behind head on develop.

Files with missing lines	Patch %	Lines
...s/messages/item/ConversationAssetPathsViewModel.kt	59.45%	8 Missing and 7 partials ⚠️
...ndroid/ui/home/conversations/model/MessageTypes.kt	0.00%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #4760   +/-   ##
========================================
  Coverage    50.79%   50.80%           
========================================
  Files          604      605    +1     
  Lines        20847    20887   +40     
  Branches      3358     3370   +12     
========================================
+ Hits         10590    10612   +22     
- Misses        9265     9276   +11     
- Partials       992      999    +7     

Files with missing lines	Coverage Δ
...ndroid/ui/home/conversations/model/MessageTypes.kt	14.28% <0.00%> (-10.72%)	⬇️
...s/messages/item/ConversationAssetPathsViewModel.kt	59.45% <59.45%> (ø)

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[sbakhtiarov]

Could we move these 'LaunchEffect' blocks into ViewModel? Like this:

    override fun localAssetPath(conversationId: ConversationId, messageId: String, assetStatus: AssetTransferStatus?): String? = localAssetPaths[messageId].also { path ->
        if (path == null && resolvingJobs[messageId]?.isActive != true) {
            resolveIfNeeded(
                conversationId = conversationId,
                messageId = messageId,
                transferStatus = assetStatus ?: AssetTransferStatus.NOT_DOWNLOADED,
                downloadIfNeeded = true,
            )
        }
    }

[sonarqubecloud]

Quality Gate passed

Issues
2 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