fix: restore window position for the intermediate airing status

The Windowstatus enum has six values, not four. Comparing the Mercedes
Android app 1.71 against the proto sources showed that the window covers
only knew 0 to 3:

  0 INTERMEDIATE, 1 COMPLETELY_OPENED, 2 COMPLETELY_CLOSED,
  3 AIRING_POSITION, 4 INTERMEDIATE_AIRING_POSITION, 5 RUNNING

WindowStatusOverall likewise has a fifth value, 4 RUNNING.

Value 4 used to map to position 50 through the old
WINDOW_STATUS_INTERMEDIATE set. The rewrite in #427 dropped it, so a
window in the intermediate airing position reported no position at all.
Restore the previous mapping.

RUNNING stays deliberately unmapped: it means the window is moving and
carries no direction, so any position would be a guess. That is now
documented instead of being an accident of a missing dict key.

Neither value appears in 121504 recorded websocket messages, so this
closes a latent gap rather than an observed failure.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: ReneNulschDE

custom_components/mbapi2020/cover.py

@@ -26,12 +26,17 @@
 from .helper import LogHelper as loghelper
 
 # Positions for the individual windows, based on the proto enum Windowstatus:
-# 0 INTERMEDIATE, 1 COMPLETELY_OPENED, 2 COMPLETELY_CLOSED, 3 AIRING_POSITION
-WINDOW_STATUS_POSITIONS: dict[int, int] = {0: 50, 1: 100, 2: 0, 3: 10}
+# 0 INTERMEDIATE, 1 COMPLETELY_OPENED, 2 COMPLETELY_CLOSED, 3 AIRING_POSITION,
+# 4 INTERMEDIATE_AIRING_POSITION, 5 RUNNING
+# RUNNING is deliberately absent: it means the window is moving and carries no
+# direction, so any position would be a guess. The entity reports unknown until
+# the car sends the status it settled on.
+WINDOW_STATUS_POSITIONS: dict[int, int] = {0: 50, 1: 100, 2: 0, 3: 10, 4: 50}
 
 # Positions for the window summary, based on the proto enum WindowStatusOverall:
-# 0 OPEN, 1 CLOSED, 2 COMPLETELY_OPEN, 3 AIRING
-# Note the numbering differs from the individual windows above
+# 0 OPEN, 1 CLOSED, 2 COMPLETELY_OPEN, 3 AIRING, 4 RUNNING
+# Note the numbering differs from the individual windows above, and RUNNING is
+# absent here for the same reason
 WINDOW_STATUS_OVERALL_POSITIONS: dict[int, int] = {0: 50, 1: 0, 2: 100, 3: 10}
 
 # Retrieval status values that indicate the car did not report a usable value