fix(cli): text-selector click by visible label + get text→body + tab --activate (#24)

Three CLI gaps surfaced driving a Mercari signup→checkout flow:

- #24-B (correctness): a bare label like 'click 購入手続きへ' was fed straight to
  document.querySelector as CSS and failed as an invalid selector, even though
  snapshot listed the button by that exact name. build_find_element_js now tries
  CSS first, then falls back to matching an interactive element by visible text
  (exact then contains) — nested and non-ASCII labels resolve. 'text=<label>'
  forces the text path. CSS still wins when it matches.
- #24-D: 'get text' with no selector now returns the whole page (body).
- #24-C: 'tab <ref> --activate' (alias --front) switches to the tab AND raises it
  to the foreground — to surface a specific tab for the human.

Tests cover the text fallback / text= / xpath builder, body default, activate
flag. The core stale-sessionId-after-cross-process-nav bug is the #20/#23 class,
already fixed in ext 0.4.8 — needs that extension deployed.

cli/src/native/actions.rs

@@ -4466,6 +4466,17 @@ async fn handle_tab_switch(cmd: &Value, state: &mut DaemonState) -> Result<Value
     state.active_frame_id = None;
     let result = mgr.tab_switch_by_id(tab_id).await?;
 
+    // `--activate`: raise this tab to the foreground (the switch made it active;
+    // bring_to_front acts on the active tab) — for handing a specific tab to the
+    // human (issue #24-C). Best-effort; don't fail the switch if it can't.
+    if cmd
+        .get("activate")
+        .and_then(|v| v.as_bool())
+        .unwrap_or(false)
+    {
+        let _ = mgr.bring_to_front().await;
+    }
+
     if let Some(ref server) = state.stream_server {
         if let Ok(dims) = mgr
             .evaluate(