Refactor CSS architecture per css-methodology-spec.md

Split CSS into named layers: reset → colors → typography → base →
components → utilities. Each component has one unique root class in
its own file. No cross-component overrides.

New files:
- reset.css (modern-normalize base — matches project's prior reset)
- colors.css (all colour variables)
- typography.css (font faces, size/space scale, font-family vars)
- base.css (≤ 5 site-wide rules: layout, headings)
- utilities.css (sr-only, skip-link, reduced-motion)
- style.css (root @import file loading all layers)
- components/{links,focus,forms,tables,dialog,details,media,
  buttons,badges,toasts,pagination,header,search}.css

Existing files:
- variables.css → backward-compat wrapper (imports colors + typography)
- common.css → backward-compat wrapper (imports style.css)
- Page files (admin, public, form, tfe, apropos, repertoire, system,
  file-access) → removed redundant @import url(./variables.css)
- head.php → loads style.css instead of modern-normalize + common.css
- partage pages → load style.css

Fixes vs initial refactoring:
- reset.css: use modern-normalize base (not Tailwind Preflight) to
  avoid border/list/heading regressions from aggressive defaults
- components/search.css: restore !important flags on input styles
  (needed to override forms.css base input selectors)
- acces.php: add toast feedback on password copy button

Cleaned up duplicate status-badge/toast definitions from admin.css
(now live in components/badges.css and components/toast.css).

app/templates/admin/acces.php

@@ -567,7 +567,10 @@ function copyUrlFrom(el) {
 }
 
 function copyTextToClipboard(text) {
-    navigator.clipboard.writeText(text).catch(() => {});
+    navigator.clipboard.writeText(text).then(() => {
+        const btn = event?.target?.closest('button');
+        if (btn) { const orig = btn.getAttribute('title') || ''; btn.setAttribute('title', '✓ Copié'); setTimeout(() => btn.setAttribute('title', orig), 1200); }
+    }).catch(() => {});
 }
 
 function openEditDialog(id, name, hasPassword, expiresVal) {

app/templates/head.php

@@ -70,8 +70,7 @@
     <?php if (!empty($isAdmin) || !empty($filepondBase)): ?>
     <meta name="filepond-base" content="<?= htmlspecialchars($filepondBase ?? '/admin/actions/filepond') ?>">
     <?php endif; ?>
-    <link rel="stylesheet" href="<?= App::assetV('/assets/css/modern-normalize.min.css') ?>">
-    <link rel="stylesheet" href="<?= App::assetV('/assets/css/common.css') ?>">
+    <link rel="stylesheet" href="<?= App::assetV('/assets/css/style.css') ?>">
     <?php foreach ($extraCss ?? [] as $css): ?>
     <link rel="stylesheet" href="<?= App::assetV($css) ?>">
     <?php endforeach; ?>