fix(line): map inbound message types to the correct MessageType

The LINE adapter classified every non-text inbound message as
`MessageType.IMAGE`, which doesn't exist on the enum — so any image,
video, audio, file, sticker, or location message raised AttributeError
the moment it was constructed.

Beyond fixing the crash, every non-text message was being collapsed onto
a single type. The gateway routes on MessageType (voice → STT, files →
document handling, etc.), so misclassification silently mishandled media.
Replace the inline ternary with a `_LINE_MESSAGE_TYPES` lookup that maps
each LINE webhook type to its proper enum member (audio → VOICE to match
how Telegram/WhatsApp treat voice notes), falling back to TEXT for
unknown types. Adds regression tests covering the mapping and the old
AttributeError.

Co-authored-by: Sahibzada Allahyar <94376830+sahibzada-allahyar@users.noreply.github.com>

plugins/platforms/line/adapter.py

@@ -133,6 +133,21 @@ MEDIA_TOKEN_TTL_SECONDS = 1800  # 30 minutes; LINE caches the URL aggressively
 LINE_IMAGE_MAX_BYTES = 10 * 1024 * 1024  # 10 MB per LINE docs
 LINE_AV_MAX_BYTES = 200 * 1024 * 1024  # 200 MB for voice/video
 
+# Map LINE webhook message types to the normalized MessageType the gateway
+# routes on. LINE has no separate "voice" type — audio messages are recorded
+# voice clips, so they map to VOICE (which the gateway sends through STT),
+# mirroring how Telegram/WhatsApp classify voice notes. Anything unknown
+# falls back to TEXT.
+_LINE_MESSAGE_TYPES = {
+    "text": MessageType.TEXT,
+    "image": MessageType.PHOTO,
+    "video": MessageType.VIDEO,
+    "audio": MessageType.VOICE,
+    "file": MessageType.DOCUMENT,
+    "location": MessageType.LOCATION,
+    "sticker": MessageType.STICKER,
+}
+
 # A 1×1 transparent PNG used as fallback video preview thumbnail when no
 # explicit preview is supplied — LINE requires ``previewImageUrl`` for
 # video messages. Sourced from the Python stdlib (no Pillow dependency).
@@ -968,7 +983,7 @@ class LineAdapter(BasePlatformAdapter):
 
         event_obj = MessageEvent(
             text=text,
-            message_type=MessageType.TEXT if msg_type == "text" else MessageType.IMAGE,
+            message_type=_LINE_MESSAGE_TYPES.get(msg_type, MessageType.TEXT),
             source=source_obj,
             raw_message=event,
             message_id=message_id,