refactor: split admin.css monolith, standardize CSS architecture
- Split admin.css (3228 lines) into 12 focused files: variables, base,
forms, buttons, layout, components, tables, skeleton, datepicker,
filemanager, pagination, responsive
- Extracted shared styles from offers.css and dashboard.css into
components.css and forms.css (offers-* → admin-* prefix)
- Standardized naming: dash-kpi-* → admin-kpi-*, session-* → dash-session-*,
rich-editor → admin-rich-editor
- Deleted duplicate offers-tabs (using admin-tabs everywhere)
- Deduplicated DatePicker and FileManager CSS (~360 lines removed)
- Added 16 utility classes to base.css (font sizes, widths, gaps, margins)
- Deleted empty admin.css
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
e0ea997c24