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/get_cohort_members.py

@@ -0,0 +1,88 @@
+#!/usr/bin/env python3
+"""Get all members who currently have the Cohort role."""
+
+import asyncio
+import json
+import os
+from pathlib import Path
+
+import aiohttp
+
+DATA_DIR = Path(__file__).parent.parent.parent / "data"
+
+DISCORD_BOT_TOKEN = os.environ["DISCORD_BOT_TOKEN"]
+GUILD_ID = "692816967895220344"
+COHORT_ROLE_ID = "1464314780935258112"
+
+
+async def get_all_members_with_role(
+    session: aiohttp.ClientSession,
+) -> list[dict[str, str]]:
+    """Get all members who have the Cohort role."""
+    members = []
+    headers = {"Authorization": f"Bot {DISCORD_BOT_TOKEN}"}
+
+    after = None
+
+    while True:
+        url = f"https://discord.com/api/v10/guilds/{GUILD_ID}/members"
+        params: dict[str, str | int] = {"limit": 1000}
+        if after:
+            params["after"] = after
+
+        async with session.get(url, headers=headers, params=params) as resp:
+            if resp.status != 200:
+                error_text = await resp.text()
+                raise RuntimeError(
+                    f"Failed to fetch members: {resp.status} - {error_text}"
+                )
+
+            data = await resp.json()
+
+            if not data:
+                break
+
+            for member in data:
+                if COHORT_ROLE_ID in member.get("roles", []):
+                    members.append(
+                        {
+                            "id": member["user"]["id"],
+                            "username": member["user"]["username"],
+                            "display_name": member.get("nick")
+                            or member["user"]["username"],
+                        }
+                    )
+
+            if len(data) < 1000:
+                break
+
+            after = data[-1]["user"]["id"]
+
+    return members
+
+
+async def main() -> None:
+    """Get all cohort members with the Cohort role."""
+    async with aiohttp.ClientSession() as session:
+        print("Fetching all members with Cohort role...")
+
+        cohort_members = await get_all_members_with_role(session)
+
+        print(f"\n✨ Found {len(cohort_members)} members with the Cohort role:\n")
+
+        for i, member in enumerate(cohort_members, 1):
+            print(
+                f"{i}. {member['display_name']} (@{member['username']}) - ID: {member['id']}"  # noqa: E501
+            )
+
+        with open(DATA_DIR / "active_cohort_members.json", "w") as f:
+            json.dump(cohort_members, f, indent=2)
+
+        print("\nSaved to active_cohort_members.json")
+
+        print("\nMember IDs only:")
+        print(json.dumps([m["id"] for m in cohort_members], indent=2))
+
+
+if __name__ == "__main__":
+    asyncio.run(main())