docs: align wire-spec and mark implemented vs proposed

Keep the 45-byte pose frame consistent across docs, simulator, and
prototype, clarify MinIO is not peer sync, and state clearly that the
repo is a from-scratch platform sketch with options rather than mandates.

simulator/virtual_drone/broadcast.py

@@ -1,12 +1,13 @@
 """State broadcast over UDP: the compact pose frame from the sync design.
 
-Frame layout (little-endian, 46 bytes):
+Frame layout (little-endian, 45 bytes) — source of truth for docs and the
+prototype bandwidth estimate:
 
     magic     2s   b"SH"
     version   B
-    drone_id  8s   zero-padded ascii
+    drone_id  8s   zero-padded ascii (PoC; production may switch to uint16 registry)
     ts_ns     q    epoch nanoseconds
-    pos_mm    3i   position, millimeters (quantized on the wire only)
+    pos_mm    3i   position in the mission frame, millimeters (wire quantization only)
     att_cdeg  3h   roll/pitch/yaw, centi-degrees
     vel_cms   3h   velocity, cm/s
     frame_ref B