3d: Attachment UI in event detail page

[ajianaz]

Parent: #233 · Blocked by: #246

Scope

Add "Attachments" section to the event detail page. Show uploaded files (screenshots, logs, minidumps) with inline preview where possible.

UI Components

Attachments Section (below event breadcrumbs/tags)

• Attachment list: card grid showing each attachment

  • File icon (by content_type: image 🖼️, text 📄, binary 📦)
  • Filename (truncated if long)
  • Size (human-readable: 2.4 MB)
  • Download button
  • Delete button (admin only)

• Inline preview:

  • Images (image/*): thumbnail with click-to-expand modal
  • Text (text/*): collapsible code block with syntax highlight
  • Other: download-only (no preview)

• Empty state: hidden when no attachments (don't show empty section)

Attachment Modal (click image thumbnail)

• Full-size image display
• Zoom controls (fit/actual)
• Download button
• Close button

API Calls

• GET /api/events/:id/attachments — fetch on page load
• GET /api/attachments/:id/download — image preview / download link
• DELETE /api/attachments/:id — delete with confirmation dialog

Tasks

• Create AttachmentList.svelte component
• Create AttachmentPreview.svelte component (image modal)
• Create AttachmentCard.svelte component (single attachment)
• Wire fetch + render in event detail +page.svelte
• Image thumbnail with lazy loading
• Text file inline preview (max 100 lines, with "show more")
• Delete with confirmation + optimistic UI update
• Empty state (no section shown when 0 attachments)
• Responsive: grid cols adapt to viewport (1→2→3→4)
• Loading skeleton while fetching

Effort: ~2 hours