feat(webui): add localized slash commands

Add a session-scoped slash command palette sourced from backend command metadata, and keep welcome-page quick actions localized across all WebUI languages.

Co-authored-by: Cursor <cursoragent@cursor.com>

webui/src/lib/api.ts

@@ -1,4 +1,4 @@
-import type { ChatSummary, SettingsPayload, SettingsUpdate } from "./types";
+import type { ChatSummary, SettingsPayload, SettingsUpdate, SlashCommand } from "./types";
 
 export class ApiError extends Error {
   status: number;
@@ -114,6 +114,27 @@ export async function fetchSettings(
   return request<SettingsPayload>(`${base}/api/settings`, token);
 }
 
+export async function listSlashCommands(
+  token: string,
+  base: string = "",
+): Promise<SlashCommand[]> {
+  type Row = {
+    command: string;
+    title: string;
+    description: string;
+    icon: string;
+    arg_hint?: string;
+  };
+  const body = await request<{ commands: Row[] }>(`${base}/api/commands`, token);
+  return body.commands.map((command) => ({
+    command: command.command,
+    title: command.title,
+    description: command.description,
+    icon: command.icon,
+    argHint: command.arg_hint ?? "",
+  }));
+}
+
 export async function updateSettings(
   token: string,
   update: SettingsUpdate,