Rewrite the modal (dialog) without Tailwind

Plan step 36 (containment group): <x-modal>'s class lists move into
resources/css/components/modal.css, keyed on data-md-modal (with
data-md-fullscreen) and data-md-modal-box/-bar/-head/-title/-subtitle/
-body/-content/-actions. Sizes stay px (560/280/48px matching
DialogTokens.kt/FullScreenDialogTokens.kt and the 56px full-screen
header, C-17), spacing the measurement tokens, breakpoints a literal
600px range query.

The phone-only header bar and the pinned head/actions keep their
existing responsive behaviour (a subtitle or an icon keeps the head on
screen below 600px; only the bar's own divider-eligibility needs a
computed flag, since it alone can sit beside a head that is also on
screen) — reproduced with :has() against data-md-icon/
data-md-modal-subtitle wherever that is self-contained, and with an
explicit data-md-modal-divider attribute where it is not. The
scroll-driven dividers rename data-dialog-head/-actions ->
data-md-modal-head/-actions, data-overflow-top/-bottom ->
data-md-overflow-top/-bottom (resources/js/dialog.js); the
dialog-dividers Alpine directive keeps its name, since it isn't a
data-md-* hook.

resources/css/components/dialog.css (Tailwind-era) is replaced by
modal.css, imported from the Containment block of components.css;
its import leaves resources/css/tailwind.css. No other component
renders <x-modal> or dialog.css's rules (checked: datepicker,
timepicker and search draw their own dialog-shaped surfaces
independently).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qwx5USif3wFFmxtHg5U1g9

resources/css/tailwind.css

@@ -17,9 +17,6 @@
 @import './tokens/theme.css';
 @import './tokens/utilities.css';
 
-/* Containment — leaving in step 36 */
-@import './components/dialog.css';
-
 /* Navigation — leaving in step 36 */
 @import './components/tabs.css';
 @import './components/app-bar.css';