Add 3 missing channels from jet-alone to channels.yml source of truth

Syncs channels.yml (canonical) and urls.txt with channels that existed
only on jet-alone: LeviathanForPlay, UCehAungJpAeC-F3R5FwvvCQ,
UC4YwC5zA9S_2EwthE27Xlew.

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

channels.yml

@@ -260,3 +260,12 @@ channels:
     handle: WavesOfObsession
     name: Wavesofobsession
     url: https://www.youtube.com/@WavesOfObsession/videos
+  - handle: LeviathanForPlay
+    name: LeviathanForPlay
+    url: https://www.youtube.com/@LeviathanForPlay/videos
+  - id: UCehAungJpAeC-F3R5FwvvCQ
+    name: Channel UCehAungJpAeC
+    url: https://www.youtube.com/channel/UCehAungJpAeC-F3R5FwvvCQ/videos
+  - id: UC4YwC5zA9S_2EwthE27Xlew
+    name: Channel UC4YwC5zA9S
+    url: https://www.youtube.com/channel/UC4YwC5zA9S_2EwthE27Xlew/videos

urls.txt

@@ -73,3 +73,6 @@ https://www.youtube.com/@rigelwindsongthurston/videos
 https://www.youtube.com/@RightInChrist/videos
 https://www.youtube.com/@RafeKelley/videos
 https://www.youtube.com/@WavesOfObsession/videos
+https://www.youtube.com/@LeviathanForPlay/videos
+https://www.youtube.com/channel/UCehAungJpAeC-F3R5FwvvCQ/videos
+https://www.youtube.com/channel/UC4YwC5zA9S_2EwthE27Xlew/videos