feat(web): unified reader with reading settings, faster lists, a11y

- New Reader (desktop + mobile): loads full content on open, prefetches
  the next article, reading progress and time, "Aa" settings (light /
  sepia / dark / auto theme, serif / sans / Atkinson Hyperlegible font,
  size, line height, measure), Space-to-next, keyboard shortcuts, focus
  management, inert background, URL-driven (?a=) so Back closes it.
- Dashboard: cursor pagination, unread/all filter, CSS grid (no masonry),
  no re-sorting under the reader, optimistic cache patches instead of
  refetch storms, "new articles" banner, error/offline states, j/k/o/m/s/v
  shortcuts and help dialog.
- Cards: keyboard-openable, lazy <img>, memoized, touch-only swipe.
- Focus mode: framer drag (drop @use-gesture), Read button, undo restores
  unread state, arrow keys.
- WebSocket: single connection, backoff, cache patching, no console logs.
- Contrast fixes (on-nature tokens), 44px targets, lang="fr", reduced
  motion, self-hosted fonts, theme applied before first paint.
- Code splitting + vendor chunk, prompt-based PWA updates, smaller
  precache, offline cache for opened articles and images, caches cleared
  on logout; upgrade react-router (CVE), drop unused deps and assets.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/components/SearchBox.tsx

@@ -0,0 +1,43 @@
+import { forwardRef, useEffect, useState } from 'react';
+
+interface SearchBoxProps {
+    onSearch: (query: string) => void;
+}
+
+/**
+ * Owns the raw input value so typing only re-renders this box; the list
+ * receives the debounced query.
+ */
+export const SearchBox = forwardRef<HTMLInputElement, SearchBoxProps>(function SearchBox({ onSearch }, ref) {
+    const [value, setValue] = useState('');
+
+    useEffect(() => {
+        const t = window.setTimeout(() => onSearch(value.trim()), 350);
+        return () => window.clearTimeout(t);
+    }, [value, onSearch]);
+
+    return (
+        <div className="relative group">
+            <span className="absolute inset-y-0 left-3 flex items-center pointer-events-none text-paper-muted group-focus-within:text-nature transition-colors">
+                <svg className="w-4 h-4" fill="none" viewBox="0 0 24 24" stroke="currentColor" aria-hidden="true">
+                    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M21 21l-6-6m2-5a7 7 0 11-14 0 7 7 0 0114 0z" />
+                </svg>
+            </span>
+            <input
+                ref={ref}
+                type="search"
+                aria-label="Rechercher dans vos articles"
+                placeholder="Rechercher…  /"
+                value={value}
+                onChange={(e) => setValue(e.target.value)}
+                onKeyDown={(e) => {
+                    if (e.key === 'Escape') {
+                        setValue('');
+                        e.currentTarget.blur();
+                    }
+                }}
+                className="input-field !py-2.5 pl-10 pr-4 !rounded-full w-full sm:w-56 sm:focus:w-72 transition-[width] text-sm"
+            />
+        </div>
+    );
+});