docs: add data file documentation and fix data path resolution

All Python cohort scripts now use DATA_DIR = Path(__file__).parent.parent.parent / "data"
to correctly resolve the repo-root data/ directory regardless of the working directory
set by run.sh. All TypeScript scripts have expanded JSDoc headers documenting data file
requirements and environment variables.

python/cohort/fix_channel_permissions.py

@@ -1,7 +1,15 @@
 #!/usr/bin/env python3
-"""Fix permissions for cohort-team-michael-and-yoon channel.
+"""Fix Send Messages / Send Messages in Threads permissions for a Discord channel.
 
-Deny Send Messages in Threads for @everyone and @cohort.
+Denies Send Messages and Send Messages in Threads for both @everyone and the
+@cohort role on the target channel. Update CHANNEL_ID and COHORT_ROLE_ID before
+running.
+
+Data files (place in data/):
+  - None
+
+Env vars:
+  - DISCORD_BOT_TOKEN  Bot token for the Discord API
 """
 
 import asyncio