DOC-8: HA manufacturer says EMS port; rebuild field guide PDF

Device id (identifiers) is unchanged; only the display text moves.
test_mqtt baseline updated for that one string.

Co-Authored-By: Claude <noreply@anthropic.com>

goodwe_controller/app/mqtt.py

@@ -29,7 +29,7 @@ _LOG = logging.getLogger("goodwe.mqtt")
 DEVICE = {
     "identifiers": ["goodwe_rs485_controller"],
     "name": "GoodWe",
-    "manufacturer": "GoodWe (via RS485 meter emulation)",
+    "manufacturer": "GoodWe (via RS485 EMS port)",
     "model": "ES/BP series",
 }