docs(espnow): update docs and tests for p2p merge

Align API, architecture, and help with devices envelope transport,
bridge wifi/serial settings, and MAC-keyed device registry. Fix
endpoint tests for envelope identify payloads; remove obsolete p2p.py.
Bump led-tool for --serial-usb bridge provisioning.

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

docs/msg.json

@@ -1,23 +1,18 @@
 {
-    "g":{ 
-        "df": {
-            "pt": "on",
-            "cl": ["#ff0000"],
-            "br": 200,
-            "n1": 10,
-            "n2": 10,
-            "n3": 10,
-            "n4": 10,
-            "n5": 10,
-            "n6": 10,
-            "dl": 100
-        },
-        "dj": {
-            "pt": "blink",
-            "cl": ["#00ff00"],
-            "dl": 500
+  "v": "1",
+  "dv": {
+    "ff:ff:ff:ff:ff:ff": {
+      "p": {
+        "2": {
+          "p": "on",
+          "c": ["#FFFFFF"],
+          "a": true
         }
-    },
-    "sv": true,
-    "st": 0
-}
+      },
+      "s": ["2", 0],
+      "g": ["5", "18"],
+      "sg": false,
+      "sv": true
+    }
+  }
+}