optimize: burst-paced Writer + tighter polls -> adb-root 6.1s -> 3.74s (settle unchanged at 0.3)

Two stability-neutral speedups, validated 6/6 on Q3 (build 52433670036000520), rebooting to clean
Enforcing between every run (all flip + adbd cred-patch + fresh shell uid0; 3.71-3.76s):

- Writer.java: replace the per-record Thread.sleep(1) with a 1ms yield every 64 sends. The reactive
  EAGAIN/ECONNREFUSED retry already handles send-buffer pressure; the proactive per-packet sleep only
  needed to cap the in-flight burst so loopback UDP receive doesn't silently drop. Capping the burst
  at 64 (below the on-device ctor's proven-safe 98 sleepless sends) keeps that guarantee while cutting
  ~1.5s off the 1467-record inject/libas poison. e2e.dex rebuilt (javac -source8 -target8 + d8 min-api30).
- orchestrate.rs: tighten the restart / enforcing-flip / adb-root-verify poll intervals from 300-400ms
  to 100ms (same total timeouts) so detection latency isn't a fixed 0.3-0.4s per stage.

poison_batch 3.2s -> ~1.7s; total --adb-root 6.1s -> 3.74s.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

java/Writer.java

@@ -129,8 +129,11 @@ public class Writer {
                         Thread.sleep(2);
                     }
                 }
-                Thread.sleep(1);   // pacing; the on-device ctor poisons sleeplessly, so 1ms is ample
                 wrote++;
+                // Pace by BURST, not per-packet: yield 1ms every 64 sends so the in-flight burst
+                // never exceeds 64 — below the on-device ctor's proven-safe 98 sleepless sends —
+                // without paying ~1ms * (records) (was the dominant cost of a large poison).
+                if ((wrote & 63) == 0) Thread.sleep(1);
             }
             r.close();
             Os.close(f);