fix: v2.5.9 — Vietnamese in the terminal on macOS, every slash command, the right Claude account

Issue #62: a tmux client whose LC_ALL/LC_CTYPE/LANG names no UTF-8 prints `_`
for every non-ASCII character, and a macOS LaunchAgent starts the dashboard
with no locale at all — Vietnamese text and Claude Code's logo came out as
underscores in every browser terminal.

- shell-path.js: ensureUtf8Locale() defaults LC_CTYPE (en_US.UTF-8 on macOS,
  C.UTF-8 elsewhere) at start, before any tmux call; an explicit LC_ALL and
  Windows are left alone
- RunSetup.tsx: the `/` list now offers Claude Code's bundled skills
  (/code-review, /security-review, /simplify, /loop…) and newer built-ins, and
  every enabled plugin's commands and skills as /<plugin>:<name>
- Claude login decided by the TOKEN's owner (GET /api/oauth/profile, cached
  per token), not by .claude.json: a running session can leave the
  credentials store holding one account's token under another account's
  name. The Profiles modal, its Check quota and the status-bar quota now show
  the account requests are really billed to and warn on the mismatch; a
  switch saves the outgoing token into its OWNER's profile (credentials only)
  instead of overwriting the profile .claude.json names; saving a profile
  while they disagree is refused (EMISMATCH); a saved profile holding another
  account's token reports EWRONGACCOUNT instead of that account's usage
- Running Claude Code sessions follow a switch on their own (they re-read the
  credentials store when it changes), so the "close your sessions first"
  warning is gone

client/src/lib/api.ts

@@ -1770,7 +1770,13 @@ export const api = {
      *   logged-in {@link CcAccountIdentity} (null when nobody is logged in).
      */
     profiles: () =>
-      request<{ items: CcProfile[]; active: CcAccountIdentity | null }>("/cc-config/profiles"),
+      request<{
+        items: CcProfile[];
+        active: CcAccountIdentity | null;
+        /** Set when the live token belongs to a different account than the
+         *  one `.claude.json` names; `active` is then the token's owner. */
+        mismatch?: { configEmail: string | null } | null;
+      }>("/cc-config/profiles"),
     /**
      * POST /api/cc-config/profiles - snapshot the logged-in account as a
      * profile. The identifier and initial label are derived from the account;