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/verify_discord.py

@@ -1,8 +1,26 @@
+"""Verify Discord user IDs from a markdown table of applicant data.
+
+Reads a markdown table containing Discord IDs and checks each one against the
+Discord API to confirm the user exists. Handles rate limits automatically.
+
+Data files (place in data/):
+  - table.md  Markdown table of applicants including a Discord ID column
+
+Outputs (written to data/):
+  - discord_verification.json  Verification result (valid/invalid) per Discord ID
+
+Env vars:
+  - DISCORD_BOT_TOKEN  Bot token for the Discord API
+"""
+
 import json
 import os
 import time
 import urllib.error
 import urllib.request
+from pathlib import Path
+
+DATA_DIR = Path(__file__).parent.parent.parent / "data"
 
 # Configuration
 BOT_TOKEN = os.environ["DISCORD_BOT_TOKEN"]
@@ -10,7 +28,7 @@ GUILD_ID = "692816967895220344"
 BASE_URL = "https://discord.com/api/v10"
 
 # Read Discord IDs from table.md
-with open("table.md") as f:
+with open(DATA_DIR / "table.md") as f:
     content = f.read()
 
 lines = content.strip().split("\n")
@@ -104,7 +122,7 @@ print(f"Missing: {len(missing)}")
 print(f"Errors: {len(errors)}")
 
 # Save results
-with open("discord_verification.json", "w") as f:
+with open(DATA_DIR / "discord_verification.json", "w") as f:
     json.dump({"verified": verified, "missing": missing, "errors": errors}, f, indent=2)
 
 print("\nResults saved to discord_verification.json")