fix(web): i18n fixes for sidebar and dropdown labels

- Add missing translation keys: skills.resultCount, skills.toolsetLabel
- Replace hardcoded "result(s)" and "toolset" with translated strings
- Fix stale useMemo in SkillsPage allCategories (missing `t` dependency)
  causing sidebar category names to stay in English after language switch

Made-with: Cursor

web/src/i18n/en.ts

@@ -170,8 +170,10 @@ export const en: Translations = {
     noSkills: "No skills found. Skills are loaded from ~/.hermes/skills/",
     noSkillsMatch: "No skills match your search or filter.",
     skillCount: "{count} skill{s}",
+    resultCount: "{count} result{s}",
     noDescription: "No description available.",
     toolsets: "Toolsets",
+    toolsetLabel: "{name} toolset",
     noToolsetsMatch: "No toolsets match the search.",
     setupNeeded: "Setup needed",
     disabledForCli: "Disabled for CLI",