Fix multiple bugs, add features and new hover effects

[Finomosec]

Summary

• Enter key in edit/add dialog now saves instead of silently closing
• ESC key closes the dialog without saving
• Icon upload during "Add Link" now works (uploaded after link creation)
• Missing vendor dependency (enshrined/svg-sanitize) — autoloader added to Application.php, Makefile fixed to include vendor in release package
• Max links per user input clamped to 1-50 with visible hint, prevents 400 error
• Duplicate link button — copies all data + icon file (server-side duplication via new POST /api/v1/admin/duplicate/{id} endpoint), opens edit dialog after
• Gear menu in dashboard widget — links to personal/admin settings, only visible to admins or when user links are enabled
• Duplicate "Visible to Groups" label removed from link form
• Effect selector — removed clearable (no "no value" state), fixed cursor on label, added hint about description requirement
• 3D Card Flip — icon rendered with object-fit: contain, original colors, rounded corners; placeholder for links without icon; only flips when description exists
• Blur Overlay / Slide Panel — icon as contain background (15% opacity, rounded corners) instead of background-size: cover
• New effect: Slide Bottom — compact dark bar from bottom edge with ellipsis
• New effect: Tooltip — tooltip bubble pops up above the link (1-3 lines)

Test plan

• Create a link with icon, verify icon upload works
• Create a link without icon, add icon later via edit
• Duplicate a link with icon, verify icon is copied
• Press Enter in edit dialog — should save
• Press ESC in edit dialog — should close without saving
• Set max links per user to >50 — should clamp to 50
• Switch between all 5 hover effects in settings, verify preview works
• Add description to a link, hover in dashboard — verify effect triggers
• Hover link without description — no effect should trigger
• Check gear icon in dashboard widget (admin and non-admin user)

🤖 Generated with Claude Code

[LexioJ]

Thanks @Finomosec — really solid contribution. Merged into release/1.3.0-rc1 for testing ahead of the 1.3.0 release.

Applied a few follow-up cleanups on top of your work:

• Gear-menu strings wrapped in t('dashlink', …) and settings links built with generateUrl() (fixes subdirectory installs)
• Removed the unused copy-icon route/controller method (duplication is fully handled server-side by duplicateLink)

The vendor//svg-sanitize packaging fix is especially appreciated. This will auto-close when 1.3.0 lands on main. Credited you in the CHANGELOG and README.