Ask breakpoints.js, not Tailwind's screens, for a window class

Plan step 16. `navigation.js` takes its standard-rail threshold from
`from('expanded')` (840px) instead of the 64rem it had, and `navigation.css`'s
three 64rem queries follow, so the whole expanded class gets the in-layout
collapsible rail M3 asks for rather than one that opens over a scrim (N-06);
its two 40rem queries become 37.5rem, the compact/medium boundary the bar's own
container query already used (N-07). `search.js` and `datepicker.js` swap their
39.99rem media strings for `upTo('medium')`, so the full-screen search view and
the modal date picker end at 600px, not 640px.

The time picker's landscape layout stops keying on width at all: M3 swaps it on
orientation and viewport height, so it is now landscape plus a window too short
for the upright dial (35rem, the dialog's own height), and the two dial-shrink
rules key on height alone.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qwx5USif3wFFmxtHg5U1g9

resources/js/datepicker.js

@@ -4,7 +4,8 @@
  *
  * The dialog is shown two ways. Docked, it is a `popover="manual"` placed under the field by CSS
  * anchor positioning; modal (the `modal` and `input` modes, and a docked picker on a compact
- * window) it is opened with `showModal()`. Everything a person sees in it is drawn by Alpine from
+ * window — below `medium`, 600px, where M3 puts the picker in a dialog rather than under the
+ * field) it is opened with `showModal()`. Everything a person sees in it is drawn by Alpine from
  * the state below, and the dialog is `wire:ignore`, so a Livewire render never touches it while
  * it is open.
  *
@@ -20,7 +21,7 @@
  * Enter selects and confirms, Escape closes and hands focus back to the field. Focus never leaves
  * the `min`–`max` span, so a disabled day cannot be chosen from the keyboard either.
  */
-const COMPACT = '(max-width: 39.99rem)'
+import { upTo } from './breakpoints.js'
 
 // CLDR's first day of the week by region, for an engine without `Intl.Locale#getWeekInfo`.
 const WEEK_STARTS_SUNDAY = 'AG AS BD BR BS BT BW BZ CA CN CO DM DO ET GT GU HK HN ID IL IN JM JP KE KH KR LA MH MM MO MT MX MZ NI NP PA PE PH PK PR PT PY SA SG SV TH TT TW UM US VE VI WS YE ZA ZW'.split(' ')
@@ -222,7 +223,7 @@ document.addEventListener('alpine:init', () => {
                 }
             })
 
-            const query = window.matchMedia(COMPACT)
+            const query = upTo('medium')
 
             this.compact = query.matches
             query.addEventListener('change', (event) => (this.compact = event.matches))