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/components/tables.css

@@ -0,0 +1,28 @@
+/* ============================================================
+   TABLES — Base table, th, td styling.
+   Root: element selectors (universal table styling)
+   ============================================================ */
+
+table {
+  width: 100%;
+  border-collapse: collapse;
+  font-size: var(--step--1);
+}
+
+th {
+  text-align: left;
+  font-size: var(--step--2);
+  letter-spacing: 0.08em;
+  text-transform: uppercase;
+  padding: var(--space-3xs) var(--space-xs);
+  border-bottom: 1px solid var(--border-primary);
+  color: var(--text-secondary);
+  font-weight: 400;
+  white-space: nowrap;
+}
+
+td {
+  padding: var(--space-2xs) var(--space-xs);
+  border-bottom: 1px solid var(--border-primary);
+  vertical-align: top;
+}