refactor(settings): remove wrapper layers, dead props and unused dictionary keys

- components/model-selector.tsx uses Dialog, Command and Tooltip
  directly; delete components/ai-elements/model-selector.tsx and
  components/button-with-tooltip.tsx; one renderGroups for both lists;
  no "Server · " prefix round trip
- components/ui: drop CommandDialog, CommandShortcut and six unused
  shadcn exports
- model-config-dialog: no type-to-confirm on provider delete;
  provider-credentials-fields: drop footer and bedrockApiKey
- hooks/use-model-config.ts and lib/types/model-config.ts: remove the
  2025-12 single-provider migration, resetConfig, selectedModel and
  fields nothing reads
- components/chat/TemplateFormDialog.tsx replaces the create and edit
  dialogs; TemplatePanel drops the setInput fallback, the
  templatesChanged listener, dictionary fallbacks and formatLastUsed;
  lib/template-storage.ts drops getTemplate, clickCount and indexes
- reasoning.tsx becomes one component; shimmer uses a CSS keyframe
  (motion and @radix-ui/react-use-controllable-state removed)
- error-toast.tsx deleted in favour of toast.error; ValidationCard
  drops the idle status; dev-xml-simulator uses English literals
- admin: no enum setting type, shared types from lib/admin
  (AdminProviderInput stays exported for that), ENABLE_HISTORY_XML_REPLACE
  entry removed
- app/globals.css: drop check-pop, --ease-spring, --duration-normal
  and the shadow aliases
- dictionaries: 81 unused keys removed from all four languages

app/api/admin/settings/route.ts

@@ -53,10 +53,6 @@ function validateValue(def: SettingDef, value: string): string | null {
             return value === "true" || value === "false"
                 ? null
                 : 'Must be "true" or "false"'
-        case "enum":
-            return def.options?.includes(value)
-                ? null
-                : `Must be one of: ${def.options?.join(", ")}`
         default:
             return null
     }