refactor: reorganise bash scripts into subdirectories and add bash runner support

Move yubikey scripts from bash/ root into bash/yubikey/, move cohort shell
scripts from python/cohort/ into bash/cohort/, and update run.sh to support
Bash as a third language with category-based script discovery.

bash/yubikey/list-yubikey-ssh-keys.sh

@@ -0,0 +1,22 @@
+#!/bin/bash
+echo "Scanning YubiKey slots for SSH keys..."
+echo "---------------------------------------------------"
+
+# Loop through the slots that support SSH keys
+for SLOT in 9a 9c 9d 9e; do
+    # Try to export the key to a temp file
+    if ykman piv keys export $SLOT /tmp/yubi_tmp.pem > /dev/null 2>&1; then
+        echo -e "\033[0;32mFOUND KEY IN SLOT $SLOT:\033[0m"
+        
+        # Check if there is a certificate label
+        LABEL=$(ykman piv certificates export $SLOT - 2>/dev/null | openssl x509 -noout -subject 2>/dev/null)
+        if [ ! -z "$LABEL" ]; then
+            echo "Certificate Label: $LABEL"
+        fi
+
+        # Convert to SSH format and print
+        ssh-keygen -i -m PKCS8 -f /tmp/yubi_tmp.pem
+        echo "---------------------------------------------------"
+        rm /tmp/yubi_tmp.pem
+    fi
+done