feat: add sort options to gallery filter (#357)

[starinsilentsky]

Summary

Adds three new sorting options to the gallery filter panel:

• Upload date (ldate) — sort by when the photo was uploaded
• Last action date (cdate) — sort by last edit/status change
• Last comment date (lcomdate) — sort by most recent comment

Closes #357

Changes

• models/Photo.js — new lcomdate field with sparse index
• controllers/photo.js — sort parameter added to filterProps and parseFilter; dynamic sort field in givePhotos
• controllers/comment.js — update lcomdate on comment add/remove
• public/js/module/photo/gallery.js — sort observable, filter string, server response handling
• views/module/photo/gallery.pug — radio button UI for sort selection
• public/js/lang/i18n.{en,ru}.json — translations for new sort labels
• controllers/__tests__/photo.sort.test.js — unit tests for sort filter parsing

Testing

npx jest --testPathPatterns=photo.sort
# 5/5 tests passed

[starinsilentsky]

Recreated with clean branch — only 8 files changed, CRLF issue fixed.

[aeifn]

The first click doesn't work:

Screen.Recording.2026-07-05.at.8.21.01.PM.mov

[aeifn]

Still works strangely:

Screen.Recording.2026-07-05.at.10.57.13.PM.mov