Add "Aller à" year-jump shortcut next to the filters

Distinct from the existing "Année" filter (which restricts the view
to just that year): this re-centers the sliding window on 1 January
of the chosen year and scrolls there, while staying in the continuous
view -- scrolling still extends the window normally in both
directions, so overlaps between years stay visible, matching the
earlier stated preference for a continuous view over a filtered one.

Resets to the placeholder immediately after firing since it's a
one-shot action, not a sticky filter. Guards against racing the
"Année" watcher's own exitYearMode() when a year filter is already
active when the jump is triggered.

web/modules/custom/figli_compta_ledger/templates/figli-compta-home.html.twig

@@ -43,6 +43,13 @@
       </select>
     </label>
 
+    <label>Aller à
+      <select v-model="jumpYearValue" @change="onJumpYearChange">
+        <option value="">Aller à…</option>
+        <option v-for="y in allYearsList" :key="y" :value="y">{{ y }}</option>
+      </select>
+    </label>
+
     <label>Regrouper par
       <select v-model="groupBy">
         <option value="none">Aucun</option>