feat(cli+mcplocal): mcpctl provider <name> {up,down,status} for managed LLMs

Adds lifecycle control for managed local LLM providers (vllm-managed)
without the nuclear option of restarting mcplocal. Practical use:

  mcpctl provider vllm-local down    # release GPU memory now
  mcpctl provider vllm-local up      # warm up before the next chat
  mcpctl provider vllm-local status  # see state, pid, uptime

mcplocal exposes three new endpoints:

  GET  /llm/providers/:name/status   → returns lifecycle state for
                                       managed providers, { managed: false }
                                       for unmanaged (anthropic, openai, …)
  POST /llm/providers/:name/start    → calls warmup() (202 + initial state)
  POST /llm/providers/:name/stop     → calls dispose() (200 + post-stop state)

Stop and start return 400 for non-managed providers — stopping an API-key
provider is meaningless. The CLI surfaces the error verbatim.

Restarting mcplocal would also free the GPU but drops the SSE connection
to mcpd and forces every virtual Llm to re-publish; this is the targeted,
non-disruptive escape hatch.

The completions test gained a `topLevelMarkers` filter so a sub-command
named `status` (under `provider`) doesn't trip the existing "non-project
commands must guard with __mcpctl_has_project" rule.

Tests: cli 437/437, mcplocal 731/731.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/cli/tests/completions.test.ts

@@ -120,7 +120,16 @@ describe('fish completions', () => {
 
   it('non-project commands do not show with --project', () => {
     const nonProjectCmds = ['status', 'login', 'logout', 'config', 'apply', 'backup'];
-    const lines = fishFile.split('\n').filter((l) => l.startsWith('complete') && l.includes('-a '));
+    // Only check top-level command lines — those are the ones whose
+    // visibility is gated on `__mcpctl_has_project`. Lines scoped to a
+    // sub-command (e.g. `provider status`) live under a different
+    // `__fish_seen_subcommand_from <parent>` predicate and don't need
+    // the project guard.
+    const topLevelMarkers = ['$commands', '$project_commands'];
+    const lines = fishFile.split('\n').filter((l) => {
+      if (!l.startsWith('complete') || !l.includes('-a ')) return false;
+      return topLevelMarkers.some((m) => l.includes(m));
+    });
 
     for (const cmd of nonProjectCmds) {
       const cmdLines = lines.filter((l) => {