feat(keys): H and L go back and forward from any page, currency selector in the header

Linking a suggested subscription on the transaction page moves from L
to y so L stays forward everywhere.

src/routes/transactions/show/[id=id]/+page.svelte

@@ -330,7 +330,7 @@
         ? [
             {
               group: "Transaction",
-              keys: "L",
+              keys: "y",
               label: `Link to the subscription ${suggestions[0].bill.attributes.name}`,
               run: link,
             },
@@ -523,7 +523,7 @@
           type="button"
         >
           {linking === "Linking" ? "Linking" : "Link it"}
-          <span class="kbd hidden lg:inline-flex">L</span>
+          <span class="kbd hidden lg:inline-flex">y</span>
         </button>
       {/if}
     </div>