Prove no Tailwind utility class remains in resources/ or tests/

StylesheetsTest.php's new test runs DesignGuard's own family table (check
(i)) over resources/views, resources/js, src, tests/Browser and
tests/Feature — the guard turned on the package's own source, so the two
never drift apart. tests/Feature/DesignGuardTest.php and
tests/Fixtures/design-guard/ carry Tailwind on purpose and are left out.

The scan found Tailwind-shaped class strings used as caller classes in 21
test files (a component test proving a caller's class lands on the root or
a caller's size wins, mostly), left over from before Tailwind cleared the
whole stack: replaced with neutral application-style names (`app-hero-icon`)
or, where one already carries the right meaning, an `md-*` class
(`md-text-end`, `md-ink-warning`). BreakpointsTest.php's own heredoc probe —
which needs a genuine Tailwind-shaped breakpoint prefix to prove its
detection works — now builds that one string from a placeholder at runtime,
so its own source stays clean for this same scan.

Plan step 42 (Phase F), Part A.

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

tests/Feature/Components/DatepickerTest.php

@@ -181,10 +181,10 @@ it('shows the value in the locale\'s numeric format before Alpine starts', funct
 });
 
 it('puts class on the root and every other attribute on the text field', function () {
-    $html = (string) $this->blade('<x-datepicker id="due" label="Due" class="w-60" required disabled variant="filled" size="sm" />');
+    $html = (string) $this->blade('<x-datepicker id="due" label="Due" class="app-due-field" required disabled variant="filled" size="sm" />');
 
     expect($html)
-        ->toContain('class="w-60"')
+        ->toContain('class="app-due-field"')
         ->toContain('data-md-variant="filled"')
         ->toContain('data-md-size="sm"')
         ->toMatch('/<input\s[^>]*required[^>]*id="due"/s')