fix(fleet): downgrade version from 13 to 12 in configuration files and scripts

fix(invidious): correct indentation in version retrieval
fix(fleet-install): switch from MariaDB to MySQL setup and update database creation logic
fix(tools): add MySQL repository handling in helper functions

misc/tools.func

@@ -894,6 +894,55 @@ Suites: $distro_codename-pgdg
 Components: main
 Architectures: $(dpkg --print-architecture)
 Signed-By: /etc/apt/keyrings/postgresql.gpg
+EOF
+    return 0
+    ;;
+
+  mysql)
+    if [[ -z "$repo_url" || -z "$gpg_key_url" ]]; then
+      msg_error "MySQL repository requires repo_url and gpg_key_url"
+      return 65
+    fi
+
+    cleanup_old_repo_files "mysql"
+
+    if ! download_gpg_key "$gpg_key_url" "/etc/apt/keyrings/mysql.gpg" "dearmor"; then
+      msg_error "Failed to import MySQL GPG key"
+      return 7
+    fi
+    chmod 644 "/etc/apt/keyrings/mysql.gpg"
+
+    local distro_codename
+    distro_codename=$(awk -F= '/^VERSION_CODENAME=/{print $2}' /etc/os-release)
+
+    if [[ "$distro_id" == "debian" ]]; then
+      case "$distro_codename" in
+      bookworm | bullseye) suite="$distro_codename" ;;
+      *) suite="bookworm" ;;
+      esac
+    elif [[ "$distro_id" == "ubuntu" ]]; then
+      case "$distro_codename" in
+      noble | jammy) suite="$distro_codename" ;;
+      *) suite="noble" ;;
+      esac
+    else
+      suite=$(get_fallback_suite "$distro_id" "$distro_codename" "$repo_url")
+    fi
+
+    local component
+    if [[ "$version" == "8.4" ]]; then
+      component="mysql-8.4-lts"
+    else
+      component="mysql-${version}"
+    fi
+
+    cat >/etc/apt/sources.list.d/mysql.sources <<EOF
+Types: deb
+URIs: ${repo_url}/
+Suites: ${suite}
+Components: ${component}
+Architectures: $(dpkg --print-architecture)
+Signed-By: /etc/apt/keyrings/mysql.gpg
 EOF
     return 0
     ;;