test(host/audio): give the reopen tests longer than the backoff they wait for

`wait_until` allowed 200 × 10 ms — exactly the 2 s `backoff_start` the reopen
path spends before it can succeed. On a warm, idle machine it wins the race;
on a cold binary or a loaded box it does not, and `reopens_after_push_death`
failed 3 of ~5 cold runs while gating this branch. CI is always cold.

Six seconds costs nothing when the test passes and only delays a genuine
failure, so the budget now clears the backoff with room to spare.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

crates/punktfunk-host/src/audio/mic_pump.rs

@@ -496,8 +496,11 @@ mod pump_tests {
         start_tuned(fail_first, false, Duration::ZERO)
     }
 
+    /// The budget has to clear `backoff_start` (2 s) with room to spare: a reopen test that
+    /// waits exactly as long as the backoff it is waiting for fails whenever the machine is
+    /// busy or the binary is cold, which is precisely what CI is.
     fn wait_until(what: &str, mut cond: impl FnMut() -> bool) {
-        for _ in 0..200 {
+        for _ in 0..600 {
             if cond() {
                 return;
             }