feat(ui): add shared media lightbox with zoom controls

[waleedlatif1]

Summary

• Open composer and sent-message image thumbnails in a shared emcn lightbox.
• Add bottom zoom controls and reuse the file viewers' trackpad pinch and scroll handling, preserving click-to-close and Escape dismissal.
• Reuse the same viewer in docs and landing content, with existing platform styling.

Type of Change

• Feature

Testing

• Tested composer and sent-image previews, trackpad gesture events, 25–400% zoom, scrolling, reset, dismissal, focus restoration, and mobile sizing in the browser.
• All eight cleanup passes complete; full-repo lint and 46 ship audits pass.
• Sim, docs, and emcn type checks pass; 64 focused lightbox, wheel, and modal tests pass.

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

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Project	Deployment	Actions	Updated
docs	Ready	Preview	Sep 15, 2026 2:14am UTC

[greptile-apps]

Confidence Score: 5/5

The PR appears safe to merge; the previous testing gap is addressed and no new actionable failure remains.

Summary

This PR consolidates image and video previews across docs, landing content, workspace attachments, and file viewers around a shared EMCN lightbox.

• Adds shared image/video lightbox rendering with modal dismissal and focus restoration.
• Adds 25–400% toolbar and trackpad zoom with pointer anchoring.
• Moves reusable wheel handling into the EMCN package.
• Migrates existing consumers and removes their local lightbox implementations.
• Adds focused interaction and wheel-helper coverage.

Diagram

%%{init: {'theme': 'neutral'}}%%
flowchart LR
  A[Docs media] --> L[Shared EMCN Lightbox]
  B[Landing images] --> L
  C[Composer attachments] --> L
  D[Sent-message images] --> L
  L --> M[EMCN Modal]
  L --> Z[Zoom controls]
  L --> W[Shared wheel helper]
  W --> F[Existing file viewers]

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_{Reviews (2) · Last reviewed commit: "fix(ui): share file viewer trackpad zoom..."}

[waleedlatif1]

@greptile

[waleedlatif1]

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[cubic-dev-ai]

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