refactor(locale): move hardcoded UI strings into english locale

Adds optional namespaces (common, errors, commandPalette, headTitle,
notifications, schedule, events, home, reader, routes, badgePreview,
badgeWall) and extends existing ones (settings.*, lists.*, tools.*,
user.*, hololive.*) on the Locale interface. New fields are optional
so japanese.ts can omit them; svelte-i18n's fallbackLocale handles
the runtime miss.

HeadTitle gains an optional routeKey prop for type-safe lookup.
defaultActions becomes a factory so the command palette re-reads
locale on language toggle. The existing JP feedback translation
in routes/settings is preserved via japanese.ts.

Out of scope (kept hardcoded): service-worker.ts, app.html,
Landing*.svelte, tools.ts registry, Easter Event 2025 pages.

1 files changed, 6 insertions, 5 deletions

diff --git a/src/routes/events/groups/+page.svelte b/src/routes/events/groups/+page.svelte
index b6181ad8..198c637b 100644
--- a/src/routes/events/groups/+page.svelte
+++ b/src/routes/events/groups/+page.svelte
@@ -5,6 +5,7 @@ import Message from "$lib/Loading/Message.svelte";
 import root from "$lib/Utility/root";
 import { onMount } from "svelte";
 import Group from "$lib/Events/Group.svelte";
+import locale from "$stores/locale";
 
 let groupsResponse: Promise<Response>;
 
@@ -16,11 +17,11 @@ const asGroup = (group: unknown) => group as GroupType;
 </script>
 
 {#await groupsResponse}
-  <Message message="Loading groups ..." />
+  <Message message={$locale().events?.loadingGroups} />
 {:then groups}
   {#if groups}
     {#await groups.json()}
-      <Message message="Parsing groups ..." />
+      <Message message={$locale().events?.parsingGroups} />
     {:then json}
       {#each json as rawGroup, i}
         {@const group = asGroup(rawGroup)}
@@ -34,11 +35,11 @@ const asGroup = (group: unknown) => group as GroupType;
         {/if}
       {/each}
     {:catch}
-      <Message message="" loader="ripple" slot withReload>Error parsing groups.</Message>
+      <Message message="" loader="ripple" slot withReload>{$locale().events?.errorParsingGroups}</Message>
     {/await}
   {:else}
-    <Message message="Parsing groups ..." />
+    <Message message={$locale().events?.parsingGroups} />
   {/if}
 {:catch}
-  <Message message="" loader="ripple" slot withReload>Error loading groups.</Message>
+  <Message message="" loader="ripple" slot withReload>{$locale().events?.errorLoadingGroups}</Message>
 {/await}