Improve template system and dialog

[CodeDoctorDE]

No description provided.

[github-actions]

Images automagically compressed by Calibre's image-actions ✨

Compression reduced images by 60.7%, saving 2.4 KB.

Filename	Before	After	Improvement	Visual comparison
app/templates/quad.png	446 B	186 B	58.3%	View diff
app/templates/ruled_dark.png	421 B	161 B	61.8%	View diff
app/templates/music_dark.png	421 B	162 B	61.5%	View diff
app/templates/quad_dark.png	443 B	186 B	58.0%	View diff
app/templates/dotted_dark.png	407 B	152 B	62.7%	View diff
app/templates/dotted.png	406 B	152 B	62.6%	View diff
app/templates/ruled.png	420 B	171 B	59.3%	View diff
app/templates/music.png	416 B	179 B	57.0%	View diff
app/templates/plain.png	346 B	126 B	63.6%	View diff
app/templates/plain_dark.png	345 B	126 B	63.5%	View diff