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/forms.css

@@ -0,0 +1,112 @@
+/* ============================================================
+   FORMS — Base input, select, textarea, fieldset, legend
+   styling shared across admin + public pages.
+   Root: element selectors (universal form styling)
+   ============================================================ */
+
+/* ── Labels ─────────────────────────────────────────────────────────── */
+
+label {
+  display: block;
+  margin-bottom: var(--space-3xs);
+}
+
+/* ── Text inputs, selects, textareas ────────────────────────────────── */
+
+input:not([type="checkbox"]):not([type="radio"]):not([type="file"]):not([type="hidden"]):not([type="submit"]):not([type="button"]):not([type="reset"]):not([type="color"]),
+textarea {
+  font-family: inherit;
+  font-size: var(--step--1);
+  padding: var(--space-2xs) var(--space-xs);
+  border: 1px solid var(--border-primary);
+  border-radius: var(--radius);
+  background: transparent;
+  color: var(--text-primary);
+  transition: border-color 0.15s;
+}
+
+input:not([type="checkbox"]):not([type="radio"]):not([type="file"]):not([type="hidden"]):not([type="submit"]):not([type="button"]):not([type="reset"]):not([type="color"]):focus,
+textarea:focus {
+  outline: none;
+  border: 2px solid var(--accent-primary);
+}
+
+input::placeholder,
+textarea::placeholder {
+  color: var(--text-tertiary);
+  font-size: var(--step--1);
+}
+
+textarea {
+  resize: vertical;
+  min-height: 80px;
+  line-height: 1.5;
+}
+
+/* ── Select ─────────────────────────────────────────────────────────── */
+
+select {
+  font-family: inherit;
+  font-size: var(--step--1);
+  padding: var(--space-2xs) var(--space-xs);
+  padding-right: 1.75rem;
+  border: 1px solid var(--border-primary);
+  border-radius: var(--radius);
+  background: transparent;
+  color: var(--text-primary);
+  cursor: pointer;
+  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'%3E%3Cpath d='M1 1l5 5 5-5' stroke='%23999' stroke-width='1.5' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
+  background-repeat: no-repeat;
+  background-position: right 0.55rem center;
+  -webkit-appearance: none;
+  appearance: none;
+  transition: border-color 0.15s;
+}
+
+select:focus {
+  outline: none;
+  border: 2px solid var(--accent-primary);
+}
+
+/* ── Checkboxes & radios ────────────────────────────────────────────── */
+
+input[type="checkbox"],
+input[type="radio"] {
+  accent-color: var(--accent-primary);
+  width: 16px;
+  height: 16px;
+  cursor: pointer;
+  flex-shrink: 0;
+  margin: 0;
+}
+
+input[type="radio"] { border-radius: 50%; }
+
+/* ── Fieldsets & legends ──────────────────────────────────────────────── */
+
+fieldset {
+  border: 1px solid var(--border-primary);
+  border-radius: var(--radius);
+  padding: 0 var(--space-m) var(--space-m) var(--space-m);
+  margin: 0;
+}
+
+fieldset > *:not(:last-child) { margin-bottom: var(--space-xs); }
+
+legend {
+  font-size: var(--step--1);
+  font-weight: 600;
+  letter-spacing: 0.04em;
+  text-transform: uppercase;
+  color: var(--text-secondary);
+  padding: 0 var(--space-2xs);
+}
+
+/* ── Small / help text ──────────────────────────────────────────────────── */
+
+small {
+  font-size: var(--step--2);
+  color: var(--text-secondary);
+  display: block;
+  margin-top: var(--space-3xs);
+}