verify(micromate): the uint32 chunk offset is confirmed -- 72,560 B in 71 chunks

UM20147's event 055d4a83 downloaded at exactly its promised size over USB,
exercising the carry into params[1] on chunks 64-70.  The uint32 reading was
inference for one commit; it is now evidence, and the 64 KB cap that would have
made this event unfetchable is closed.

Worth noting what the same run prices: 71 chunks x ~0.65 s is roughly 46 SECONDS
for one 72 KB histogram over cellular, against 0.2 s over USB.  That is the
round-trip cost model doing real work -- the bytes are nothing, the commands are
everything.  A unit holding several events this size is a multi-minute call, so
the untested single-request offset_hi = 0x10 streaming mode (which would collapse
a download to one round trip) moves up the list.

Docstrings and the protocol reference downgraded from "inference" to "confirmed"
only where the hardware actually settled it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ru8Lg9HkkYvX9VWWo65SmL

tests/test_micromate_protocol.py

@@ -442,7 +442,12 @@ def test_a_chunk_offset_with_0x10_in_it_is_escaped_on_the_wire():
 
 
 def test_a_72kb_event_downloads_in_71_chunks():
-    """UM20147's event 055d4a83, the one that broke the uint16 assumption."""
+    """UM20147's event 055d4a83, the one that broke the uint16 assumption.
+
+    ✅ Confirmed against the real unit 2026-10-01: 71 chunks, exact size, with
+    chunks 64-70 carrying 0x01 in params[1].  This test pins the arithmetic the
+    hardware agreed with.
+    """
     size = 72560
     n = 71
     responses = []