Replace UU-uploads playlist workaround (proto field 104) with direct
requests to the channel Videos tab API (tab="videos"), aligning with
Invidious content-type handling. This restores proper continuation
tokens and stable pagination (~30 videos per page).
Update display logic:
- Show channel total upload count as an upper-bound while continuation
tokens exist.
- On final page, display exact fetched video count.
- Ensure page number never falls below current page (fix page reset to "1").
Maintain separate handling:
- Shorts and streams tabs continue using tab-specific continuation tokens.
Add test:
- TestChannelCtokenV5::test_include_shorts_false_adds_filter
Fixes issue where channels with many Shorts (e.g., Celine Dept) showed
only a few videos and broken pagination under "no shorts" sorting.
18 tests covering:
- channel_ctoken_v5 protobuf token generation per tab
- shortsLockupViewModel parsing (id, title, thumbnail, type)
- View count formatting with K/M/B suffixes
- extract_items with reloadContinuationItemsCommand response format
All tests run offline with mocked data, no network access.
