feat(espnow): Pi bridge client, binary wire, and espnow-sender firmware

Replace serial/Wi-Fi driver transport paths with WebSocket bridge client,
binary espnow_wire delivery, device announce registry, and restructured
espnow-sender (AP + broadcast passthrough). Includes docs and tests.

Co-authored-by: Cursor <cursoragent@cursor.com>

espnow-sender/lib/microdot/helpers.py

@@ -0,0 +1,8 @@
+try:
+    from functools import wraps
+except ImportError:  # pragma: no cover
+    # MicroPython does not currently implement functools.wraps
+    def wraps(wrapped):
+        def _(wrapper):
+            return wrapper
+        return _