fix: Conversation images previews do not seem to use actual server-provided previews, but original image(WPB-22331)

[arjita-mitra]

WPB-22331 [Web] Conversation images previews do not seem to use actual server-provided previews, but original image

Pull Request

Summary

• Small image cards (multiple images in one message): continue using src={filePreviewUrl} correct for grid display, no change.

• Large image cards (single image in a message): now use the original fileUrl, falling back to filePreviewUrl only if unavailable.

• Fullscreen viewer: now uses the original fileUrl instead of the thumbnail.

HEIC handling

HEIC files uploaded from iOS cannot be decoded natively by Chrome, Firefox, or Edge. For these files, isPreviewableImage({extension}) returns false, so both the large card and fullscreen fall back to filePreviewUrl the server-generated JPEG conversion which is safe across all browsers. The original HEIC file is still accessible via the download button in the fullscreen header.

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Security Checklist (required)

• External inputs are validated & sanitized on client and/or server where applicable.
• API responses are validated; unexpected shapes are handled safely (fallbacks or errors).
• No unsafe HTML is rendered; if unavoidable, sanitization is applied and documented where it happens.
• Injection risks (XSS/SQL/command) are prevented via safe APIs and/or escaping.

Accessibility (required)

• I have read and this PR upholds our Accessibility Best Practices.

Standards Acknowledgement (required)

• I have read and this PR upholds our Coding Standards and Tech Radar Choices.

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Screenshots or demo (if the user interface changed)

Notes for reviewers

• Trade-offs:
• Follow-ups (linked issues):
• Linked PRs (e.g. web-packages):

[github-actions]

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🧪 Playwright Test Summary

• ✅ Passed: 10
• ❌ Failed: 0
• ⏭ Skipped: 3
• 🔁 Flaky: 1
• 📊 Total: 14
• ⏱ Total Runtime: 96.8s (~ 1 min 37 sec)

specs/CriticalFlow/addMembersToChat-TC-8631.spec.ts (❌ 0 failed, ⚠️ 1 flaky)

• ⚠️ Team owner adds whole team to an all team chat (tags: TC-8631, crit-flow-web)

[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