Auto-join groups: /g and /gjoin auto-create if group doesn't exist

- Server: /join endpoint creates the group if it doesn't exist
- CLI TUI: /g <name> auto-joins before switching
- Web: /g <name> auto-joins before switching
- No more "group not found" errors — just /g ops and go

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

warzone/crates/warzone-server/src/routes/web.rs

@@ -413,6 +413,8 @@ async function groupJoin(name) {
 }
 
 async function groupSwitch(name) {
+  // Auto-join
+  await groupJoin(name);
   const resp = await fetch(SERVER + '/v1/groups/' + name);
   const data = await resp.json();
   if (data.error) { addSys('Error: ' + data.error); return; }