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/discord_activity_checker.py

@@ -1,6 +1,17 @@
 #!/usr/bin/env python3
-"""Discord Team Activity Checker
-Checks for team members who haven't sent messages in their channels within 36 hours
+"""Check for team members who have not sent a message in their channel within 36 hours.
+
+Scans each team's Discord channel and flags members with no recent activity.
+Optionally sends a direct mention message to inactive members.
+
+Data files (place in data/):
+  - team_assignments.json  Team rosters with leaders and participants per team
+
+Outputs (written to data/):
+  - discord_activity_report.json  Inactive members per team with last-seen timestamps
+
+Env vars:
+  - DISCORD_BOT_TOKEN  Bot token for the Discord API
 """
 
 import asyncio
@@ -8,16 +19,19 @@ import json
 import os
 import sys
 from datetime import datetime, timedelta, timezone
+from pathlib import Path
 
 import aiohttp
 
+DATA_DIR = Path(__file__).parent.parent.parent / "data"
+
 # Configuration
 DISCORD_TOKEN = os.environ["DISCORD_BOT_TOKEN"]
 DISCORD_API_BASE = "https://discord.com/api/v10"
 INACTIVE_THRESHOLD_HOURS = 36
 
 # Load team assignments from file
-with open("team_assignments.json") as f:
+with open(DATA_DIR / "team_assignments.json") as f:
     team_data = json.load(f)
 
 # Build TEAMS dictionary with channel IDs and member lists
@@ -233,7 +247,7 @@ async def main():
         print("\n" + "=" * 80)
 
         # Save results to JSON
-        with open("discord_activity_report.json", "w") as f:
+        with open(DATA_DIR / "discord_activity_report.json", "w") as f:
             json.dump(
                 {
                     "generated_at": datetime.now(timezone.utc).isoformat(),