feat: reorganise bash scripts and add comprehensive documentation (#6)

## Summary

This PR completes the bash script restructuring and adds comprehensive documentation across all script categories.

### Bash Restructuring

- Moved cohort shell scripts (`remove_github_members.sh`, `update_github_teams.sh`) from `python/cohort/` into a new `bash/cohort/` directory
- Moved existing bash utilities (`add-keys-to-git.sh`, `fix-yubikey-perms.sh`, `list-yubikey-ssh-keys.sh`) into a new `bash/yubikey/` subdirectory
- Updated `run.sh` to support **Bash** as a third language option alongside TypeScript and Python
  - Bash scripts are run directly (no 1Password secret injection needed)
  - Category discovery and script listing works the same as for TS/Python
  - Removed dead "Root Scripts" logic that was no longer needed

### Documentation

Added `README.md` files for all script categories that were missing them:

- `bash/cohort/README.md` — cohort GitHub team management scripts
- `bash/yubikey/README.md` — YubiKey SSH key and permission utilities
- `typescript/src/crowdin/README.md` — Crowdin translation management scripts
- `typescript/src/discord/README.md` — Discord bot utility scripts
- `typescript/src/discourse/README.md` — Discourse forum management scripts
- `typescript/src/gitea/README.md` — Gitea bulk repository operation scripts
- `typescript/src/github/README.md` — GitHub API interaction scripts
- `typescript/src/music/README.md` — Music file metadata tools
- `typescript/src/s3/README.md` — S3-compatible object storage scripts
- `typescript/src/security/README.md` — Security analysis and reporting scripts
- `python/cohort/README.md` — Updated to remove moved shell scripts, fix usage commands

Also updated project-level docs:

- **`README.md`** — Corrected project structure, fixed running instructions (removed references to non-existent `make run-ts`/`make run-py` targets), added Bash prerequisites
- **`CLAUDE.md`** — Updated project overview, structure, development standards, and script-adding guides to reflect the current state of the project

✨ This PR was created with help from Hikari~ 🌸

Co-authored-by: Naomi Carrigan <commits@nhcarrigan.com>
Reviewed-on: #6
Co-authored-by: Hikari <hikari@nhcarrigan.com>
Co-committed-by: Hikari <hikari@nhcarrigan.com>

python/cohort/check_member_status.py

@@ -0,0 +1,49 @@
+#!/usr/bin/env python3
+"""Check if removed members are still in the Discord server."""
+
+import asyncio
+import os
+
+import aiohttp
+
+DISCORD_BOT_TOKEN = os.environ["DISCORD_BOT_TOKEN"]
+BASE_URL = "https://discord.com/api/v10"
+GUILD_ID = "1354624415861833870"
+
+SAMPLE_MEMBERS = [
+    "899092786802987069",
+    "1318882254365397032",
+    "799293680799711273",
+    "237793557992308736",
+]
+
+
+async def check_member(session: aiohttp.ClientSession, user_id: str) -> bool | None:
+    """Check if a member is in the server."""
+    url = f"{BASE_URL}/guilds/{GUILD_ID}/members/{user_id}"
+    headers = {"Authorization": f"Bot {DISCORD_BOT_TOKEN}"}
+
+    async with session.get(url, headers=headers) as resp:
+        if resp.status == 200:
+            data = await resp.json()
+            roles = data.get("roles", [])
+            print(f"✅ User {user_id} IS in server - has {len(roles)} roles: {roles}")
+            return True
+        if resp.status == 404:
+            print(f"❌ User {user_id} NOT in server (left or was kicked)")
+            return False
+        error = await resp.text()
+        print(f"⚠️  Error checking {user_id}: {resp.status} - {error}")
+        return None
+
+
+async def main() -> None:
+    """Check if sample members are still in the server."""
+    async with aiohttp.ClientSession() as session:
+        for user_id in SAMPLE_MEMBERS:
+            await check_member(session, user_id)
+            await asyncio.sleep(1)
+
+
+if __name__ == "__main__":
+    asyncio.run(main())