feat: add year filter to main index

- Footer now displays all available years horizontally with scroll
- Click on year filters thesis list to that year
- Active year highlighted in footer
- 'Tous' link to reset filter
- Filter info banner shows when year selected with reset button
- Pagination preserves year filter
- Styled with horizontal scroll, smooth scrollbar
- Tests passing ✅

public/assets/main.css

@@ -13,7 +13,8 @@ main {
   height: 60vh;
 }
 footer {
-  height: 20vh;
+  height: 10vh;
+  font-size: 0.8em;
 }
 
 body {
@@ -51,6 +52,33 @@ header .title, header section, header nav {
   text-decoration: none;
   line-height: 2.5rem;
 }
+
+/* Filter info banner */
+.filter-info {
+  background: rgba(149, 87, 181, 0.9);
+  color: white;
+  padding: 0.5rem 1rem;
+  text-align: center;
+  font-size: 0.9rem;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 1rem;
+}
+
+.clear-filter {
+  color: white;
+  text-decoration: none;
+  padding: 0.25rem 0.75rem;
+  background: rgba(0, 0, 0, 0.2);
+  border-radius: 15px;
+  font-size: 0.85rem;
+  transition: background 0.2s;
+}
+
+.clear-filter:hover {
+  background: rgba(0, 0, 0, 0.4);
+}
 main {
   height: 60vh;
 
@@ -80,6 +108,57 @@ main {
 
 footer {
   background: #222222ff;
+  overflow: hidden;
+}
+
+/* Years navigation in footer */
+.years-nav {
+  height: 100%;
+  display: flex;
+  align-items: center;
+}
+
+.years-scroll {
+  display: flex;
+  gap: 1rem;
+  overflow-x: auto;
+  overflow-y: hidden;
+  scroll-behavior: smooth;
+  padding: 0.5rem 0;
+  width: 100%;
+}
+
+/* Hide scrollbar but keep functionality */
+.years-scroll::-webkit-scrollbar {
+  height: 4px;
+}
+
+.years-scroll::-webkit-scrollbar-track {
+  background: transparent;
+}
+
+.years-scroll::-webkit-scrollbar-thumb {
+  background: rgba(255, 255, 255, 0.3);
+  border-radius: 2px;
+}
+
+.year-link {
+  color: white;
+  text-decoration: none;
+  padding: 0.5rem 1rem;
+  border-radius: 20px;
+  white-space: nowrap;
+  transition: background 0.2s;
+  font-size: 1rem;
+}
+
+.year-link:hover {
+  background: rgba(255, 255, 255, 0.1);
+}
+
+.year-link.active {
+  background: #9557b5ff;
+  font-weight: bold;
 }
 
 /* .card { */