Fix trailing spaces and missing newlines in all mcu-*.yaml files

Bulk cleanup: remove trailing whitespace and ensure files end with a
newline. Structural issues (indentation, bracket spacing) left for
per-file fixes.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

mcu-echo-1.yaml

@@ -20,11 +20,11 @@ esp32:
     # type: esp-idf
     # version: 5.1.2
     # platform_version: 6.5.0
-    
+
 
 external_components:
   - source: components
-  # - source: 
+  # - source:
   #     type: git
   #     url: https://github.com/nielsnl68/esphome
   #     ref: nvds-RTTTL_I2S
@@ -94,14 +94,14 @@ light:
 #           condition:
 #              lambda: return state > 0;
 #           then:
-#             - light.turn_on: 
+#             - light.turn_on:
 #                 id: neo_buildin
 #                 red: 1.0
 #                 green: 0.0
 #                 blue: 0.0
 #                 brightness: 100%
 #           else:
-#             - light.turn_off: 
+#             - light.turn_off:
 #                 id: neo_buildin
 #                 # green: 0.0
 #                 # red: 0.0
@@ -134,7 +134,7 @@ speaker:
 rtttl:
   id: my_rtttl
   speaker: echo_speaker
-  
+
 microphone:
   - platform: i2s_audio
     id: echo_microphone
@@ -148,4 +148,4 @@ voice_assistant:
     - media_player.play_media:
         id: media_out
         media_url: !lambda |-
-          return x;
+          return x;