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/public/assets/css/admin.css

@@ -116,7 +116,7 @@
     margin-top: var(--space-l);
 }
 
-/* ── Admin button aliases — see common.css .btn base class ────────────── */
+/* ── Admin button aliases — see components/buttons.css .btn base class ─── */
 
 .admin-btn {
     /* deprecated alias for .btn--primary; kept for backward-compat */
@@ -138,67 +138,7 @@
     /* deprecated alias for .btn--danger; kept for backward-compat */
 }
 
-/* ── Toast messages (bottom-center, CSS-only auto-fade) ─────────────── */
-#toast-region {
-    position: fixed;
-    bottom: var(--space-l);
-    left: 50%;
-    transform: translateX(-50%);
-    z-index: 10000;
-    display: flex;
-    flex-direction: column;
-    align-items: center;
-    gap: var(--space-xs);
-    pointer-events: none;
-    width: max-content;
-    max-width: min(560px, calc(100vw - 2 * var(--space-l)));
-}
-
-.toast {
-    padding: var(--space-s) var(--space-m);
-    border-radius: var(--radius);
-    font-size: var(--step-0);
-    border-left: 4px solid;
-    box-shadow: 0 6px 24px rgba(0, 0, 0, 0.25);
-    pointer-events: auto;
-    /* enter then fade out — total visible ~6.35 s */
-    animation: toast-enter 0.35s ease-out,
-               toast-exit  0.5s  ease-in  6s forwards;
-}
-
-.toast--error {
-    background: var(--bg-secondary);
-    border-color: var(--error);
-    color: var(--text-primary);
-}
-
-.toast--success {
-    background: var(--bg-secondary);
-    border-color: var(--success);
-    color: var(--text-primary);
-}
-
-.toast--warning {
-    background: var(--bg-secondary);
-    border-color: var(--warning);
-    color: var(--text-primary);
-    animation: toast-enter 0.35s ease-out; /* no fade-out — stays until dismissed */
-}
-
-.toast--warning a {
-    color: inherit;
-    text-decoration: underline;
-}
-
-@keyframes toast-enter {
-    from { opacity: 0; transform: translateY(12px); }
-    to   { opacity: 1; transform: translateY(0); }
-}
-
-@keyframes toast-exit {
-    from { opacity: 1; }
-    to   { opacity: 0; pointer-events: none; }
-}
+/* ── Toast messages — styles in components/toast.css ───────────────── */
 
 /* ── Stats cards ────────────────────────────────────────────────────────── */
 .admin-stats {
@@ -352,7 +292,7 @@
 }
 
 /* ── Table ──────────────────────────────────────────────────────────────── */
-/* Base table/th/td styles live in common.css */
+/* Base table/th/td styles live in components/tables.css */
 .admin-body main > table {
     margin-top: var(--space-m);
 }
@@ -406,52 +346,10 @@ th.admin-ap-col {
 }
 
 /* ── Status badges ──────────────────────────────────────────────────────── */
-.status-badge {
-    display: inline-block;
-    padding: var(--space-3xs) var(--space-2xs);
-    border-radius: var(--radius);
-    font-size: var(--step--2);
-    font-weight: 500;
-    letter-spacing: 0.04em;
-}
+/* ── Status badges — base styles in components/badges.css ─────────── */
 
-.status-published {
-    background: var(--green-muted-bg);
-    color: var(--accent-green);
-}
-
-.status-pending {
-    background: var(--warning-muted-bg);
-    color: var(--warning);
-}
-
-.status-access {
-    display: inline-block;
-    font-size: var(--step--2);
-    padding: var(--space-3xs) var(--space-3xs);
-    border-radius: var(--radius);
-    background: var(--bg-tertiary);
-    color: var(--text-secondary);
-    letter-spacing: 0.03em;
-}
-
-.status-access--libre {
-    background: var(--green-muted-bg);
-    color: var(--accent-green);
-}
-
-.status-access--interne {
-    background: var(--blue-muted-bg);
-    color: var(--accent-blue);
-}
-
-.status-access--interdit {
-    background: var(--error-muted-bg);
-    color: var(--error);
-}
-
-/* ── Compact table badges ─────────────────────────────────────────── */
-.status-badge {
+/* ── Compact table badges (admin-only override) ──────────────────── */
+.admin-body .status-badge {
     font-size: 0.7rem;
     padding: 2px var(--space-3xs);
 }
@@ -541,7 +439,7 @@ th.admin-ap-col {
     border-color: var(--yellow-muted-border);
 }
 
-/* ── Action buttons in table — see common.css .btn base class ──────────── */
+/* ── Action buttons in table — see components/buttons.css .btn base class ─ */
 .admin-actions {
     display: flex;
     gap: var(--space-3xs);
@@ -1030,7 +928,7 @@ th.admin-ap-col {
 }
 
 /* ── Dialog ───────────────────────────────────────────────────────────── */
-/* Base dialog/::backdrop styles live in common.css */
+/* Base dialog/::backdrop styles live in components/dialog.css */
 .admin-dialog {
     max-width: 680px;
     width: 100%;