feat(claude): active-project status line + /mcpctl switcher, and stop tests writing to ~/.claude

Claude Code had neither of the things opencode, pi and prime-agent all have: a
visible active project, and a way to change it from inside a session. It has no
plugin API that can draw a widget or open a picker, but it does run a command
for its status line and it does load slash commands — which is enough for both.

  - `mcpctl statusline` prints the active project (from .mcp.json, falling back
    to a .mcpctl-project marker) and is wired into settings.json. It reads the
    directory out of the JSON Claude Code pipes in, so it follows /cwd rather
    than reporting wherever the binary was launched. Prints nothing when no
    project is active: an empty line beats "none" on every unrelated repo.
  - `/mcpctl [project]` switches and reminds you to reconnect from /mcp.
    allowed-tools is scoped to the four exact mcpctl invocations it needs.

Three things found by running it rather than reasoning about it:

  - Claude Code REWRITES settings.json against its own schema and strips
    unknown keys from `statusLine` — our `_mcpctl_managed` marker came back
    gone, so ownership is now determined by the command string. (Hooks keep
    their marker; statusLine does not.) A composed line like
    `my-prompt && mcpctl statusline` is deliberately not claimed.
  - Every `!`-prefixed block in a slash command is permission-checked against
    allowed-tools. Omitting `statusline` failed the whole command before the
    model saw anything. A test now asserts every pre-executed command is
    covered.
  - Setting ANTHROPIC_AUTH_TOKEN *and* ANTHROPIC_API_KEY makes Claude Code warn
    that auth may not work; claude-vllm now sets only the former and clears an
    inherited API key.

Also fixes a pre-existing test-isolation bug this work would have made worse:
`config claude` wrote into the developer's real ~/.claude when the suite ran,
which is how an untagged duplicate of the skills-sync SessionStart hook got
there. Both the hook installer and the new UI installers now honour
CLAUDE_CONFIG_DIR (Claude Code's own override — correct behaviour first,
isolation second), `config claude` gains --claude-dir for parity with --pi-dir
and --opencode-dir, and the suite is verified to leave ~/.claude byte-identical.

Verified live: status line renders `mcpctl:homeautomation`, `/mcpctl docmost`
switches and the line updates to `mcpctl:docmost` in the same session.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BVwuCjuMoA13gmzYEfcrNP

src/cli/tests/commands/claude.test.ts

@@ -21,14 +21,29 @@ describe('config claude', () => {
   let tmpDir: string;
   const log = (...args: string[]) => output.push(args.join(' '));
 
+  /**
+   * Claude Code's config dir, redirected per test.
+   *
+   * Without this the suite writes a SessionStart hook, a status line and a
+   * slash command into the developer's real ~/.claude — which is exactly how an
+   * untagged duplicate of the skills-sync hook ended up there.
+   */
+  let claudeDir: string;
+  let priorClaudeConfigDir: string | undefined;
+
   beforeEach(() => {
     client = mockClient();
     output = [];
     tmpDir = mkdtempSync(join(tmpdir(), 'mcpctl-config-claude-'));
+    claudeDir = join(tmpDir, 'claude-home');
+    priorClaudeConfigDir = process.env['CLAUDE_CONFIG_DIR'];
+    process.env['CLAUDE_CONFIG_DIR'] = claudeDir;
   });
 
   afterEach(() => {
     rmSync(tmpDir, { recursive: true, force: true });
+    if (priorClaudeConfigDir === undefined) delete process.env['CLAUDE_CONFIG_DIR'];
+    else process.env['CLAUDE_CONFIG_DIR'] = priorClaudeConfigDir;
   });
 
   it('generates .mcp.json with mcpctl mcp bridge entry', async () => {