Add API tokens, CLI server API and shared core crate

- Personal API tokens (full/read scope, expiry, revoke) and CLI password login
- Cargo workspace: codecraft-core (types, providers, permission rules) shared by
  server and the upcoming terminal client; server re-exports the old paths
- CLI server API: /cli/config, /cli/skill, /cli/tool (server MCP tools),
  /llm/stream model gateway with budgets and usage per user
- Theme/language preferences mirrored to the server; personal memory endpoint
- Statistics: provider and mode tables stacked; CLI usage labelled
- cli/: work in progress (terminal client is being rewritten as a local TUI)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/i18n/index.ts

@@ -25,6 +25,11 @@ let current = detect();
 document.documentElement.lang = current;
 const listeners = new Set<() => void>();
 
+export function onLangChange(fn: () => void) {
+  listeners.add(fn);
+  return () => void listeners.delete(fn);
+}
+
 export function getLang() {
   return current;
 }