fix(channels): the Length column shows the sum alone

The "+N without length" line did not fit the 4.5 rem column (88 px of
text in a 56 px cell) and spilled into Tags. The owner wants no such
line there: the cell shows the summed hours, and the channel list no
longer sends a count nothing reads. A playlist's total keeps it.

backend/app/catalog/queries.py

@@ -44,8 +44,8 @@ def channel_titles(db: Session, ids: set[str]) -> dict[str, str]:
 
 
 def channel_aggregates(channel_ids: list[str]) -> Select:
-    """Per-channel stored count, last upload, total duration and the live videos the total cannot
-    hold (`Video.live_without_length`), in one grouped pass. Every column it
+    """Per-channel stored count, last upload and total duration (the lengths it knows: a video with
+    none is left out, `Video.length_seconds`), in one grouped pass. Every column it
     reads is in `ix_videos_channel_pub_cover` (migration 0095), so Postgres answers it from the index
     alone; a test holds that (test_channel_list_index_only)."""
     return (
@@ -54,18 +54,14 @@ def channel_aggregates(channel_ids: list[str]) -> Select:
             func.count(Video.id),
             func.max(Video.published_at),
             func.coalesce(func.sum(Video.length_seconds), 0),
-            func.count().filter(Video.live_without_length),
         )
         .where(Video.channel_id.in_(channel_ids))
         .group_by(Video.channel_id)
     )
 
 
-def aggregates(
-    db: Session, channel_ids: list[str]
-) -> list[tuple[str, int, datetime | None, int, int]]:
-    """`channel_aggregates`, run: (channel id, stored videos, last upload, total seconds, live
-    videos without a length)."""
+def aggregates(db: Session, channel_ids: list[str]) -> list[tuple[str, int, datetime | None, int]]:
+    """`channel_aggregates`, run: (channel id, stored videos, last upload, total seconds)."""
     if not channel_ids:
         return []
     return list(db.execute(channel_aggregates(channel_ids)).tuples())