feat(app): show skill/mcp badges for slash commands

Display 'skill' or 'mcp' badge instead of 'custom' for slash commands
based on their source type. This provides better clarity to users about
where each command comes from.

packages/app/src/i18n/en.ts

@@ -216,6 +216,8 @@ export const dict = {
   "prompt.popover.emptyCommands": "No matching commands",
   "prompt.dropzone.label": "Drop images or PDFs here",
   "prompt.slash.badge.custom": "custom",
+  "prompt.slash.badge.skill": "skill",
+  "prompt.slash.badge.mcp": "mcp",
   "prompt.context.active": "active",
   "prompt.context.includeActiveFile": "Include active file",
   "prompt.context.removeActiveFile": "Remove active file from context",