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.

3 files changed, 22 insertions, 19 deletions

diff --git a/src/routes/events/+page.svelte b/src/routes/events/+page.svelte
index 88a3da9e..0474852b 100644
--- a/src/routes/events/+page.svelte
+++ b/src/routes/events/+page.svelte
@@ -4,13 +4,14 @@ import Event from "$lib/Events/Event.svelte";
 import Message from "$lib/Loading/Message.svelte";
 
 import root from "$lib/Utility/root";
+import locale from "$stores/locale";
 </script>
 
 {#await fetch(root(`/api/events`))}
-  <Message message="Loading events ..." />
+  <Message message={$locale().events?.loadingEvents} />
 {:then eventsResponse}
   {#await eventsResponse.json()}
-    <Message message="Parsing events ..." />
+    <Message message={$locale().events?.parsingEvents} />
   {:then events}
     {#if events}
       {#each events as rawEvent, i}
@@ -22,6 +23,6 @@ import root from "$lib/Utility/root";
       {/each}
     {/if}
   {:catch}
-    <Message message="" loader="ripple" slot withReload>Error parsing events.</Message>
+    <Message message="" loader="ripple" slot withReload>{$locale().events?.errorParsingEvents}</Message>
   {/await}
 {/await}
diff --git a/src/routes/events/group/[group]/+page.svelte b/src/routes/events/group/[group]/+page.svelte
index c02c1b51..34db0fae 100644
--- a/src/routes/events/group/[group]/+page.svelte
+++ b/src/routes/events/group/[group]/+page.svelte
@@ -7,6 +7,7 @@ import root from "$lib/Utility/root";
 import { onMount } from "svelte";
 import Group from "$lib/Events/Group.svelte";
 import Event from "$lib/Events/Event.svelte";
+import locale from "$stores/locale";
 import type { PageData } from "./$types";
 
 export let data: PageData;
@@ -23,16 +24,16 @@ const asEvent = (event: unknown) => event as EventType;
 </script>
 
 {#await groupsResponse}
-  <Message message="Loading group ..." />
+  <Message message={$locale().events?.loadingGroup} />
 {:then group}
   {#if group}
     {#await group.json()}
-      <Message message="Parsing group ..." />
+      <Message message={$locale().events?.parsingGroup} />
     {:then json}
       {#if json === null}
         <Message message="" loader="ripple" slot>
-          This group may not exist. Please
-          <a href={'#'} onclick={() => location.reload()}>try again</a> later.
+          {$locale().events?.groupNotExistPrefix}
+          <a href={'#'} onclick={() => location.reload()}>{$locale().common?.tryAgain}</a>{$locale().events?.groupNotExistSuffix}
         </Message>
       {:else}
         {@const group = asGroup(json)}
@@ -42,13 +43,13 @@ const asEvent = (event: unknown) => event as EventType;
         <Spacer />
 
         <details open>
-          <summary>Events</summary>
+          <summary>{$locale().events?.summary}</summary>
 
           {#await fetch(root(`/api/events?group=${data.group}`))}
-            <Message message="Loading events ..." />
+            <Message message={$locale().events?.loadingEvents} />
           {:then eventsResponse}
             {#await eventsResponse.json()}
-              <Message message="Parsing events ..." />
+              <Message message={$locale().events?.parsingEvents} />
             {:then events}
               {#if events}
                 {#each events as rawEvent, i}
@@ -60,17 +61,17 @@ const asEvent = (event: unknown) => event as EventType;
                 {/each}
               {/if}
             {:catch}
-              <Message message="" loader="ripple" slot withReload>Error parsing events.</Message>
+              <Message message="" loader="ripple" slot withReload>{$locale().events?.errorParsingEvents}</Message>
             {/await}
           {/await}
         </details>
       {/if}
     {:catch}
-      <Message message="" loader="ripple" slot withReload>Error parsing group.</Message>
+      <Message message="" loader="ripple" slot withReload>{$locale().events?.errorParsingGroup}</Message>
     {/await}
   {:else}
-    <Message message="Parsing groups ..." />
+    <Message message={$locale().events?.parsingGroups} />
   {/if}
 {:catch}
-  <Message message="" loader="ripple" slot withReload>Error loading group.</Message>
+  <Message message="" loader="ripple" slot withReload>{$locale().events?.errorLoadingGroup}</Message>
 {/await}
diff --git a/src/routes/events/groups/+page.svelte b/src/routes/events/groups/+page.svelte
index b6181ad8..198c637b 100644
--- a/src/routes/events/groups/+page.svelte
+++ b/src/routes/events/groups/+page.svelte
@@ -5,6 +5,7 @@ import Message from "$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}