Improve shell script safety and error handling

[shbhmexe]

Summary

This PR delivers two focused, low-risk fixes that improve safety and correctness of shell scripts without changing any features:

1. util_sh/db_data_mv.sh

• Add strict mode (set -euo pipefail).
• Validate input argument (non-empty, directory must exist) and guard dangerous operations.
• Create destination parent directories to avoid cp failures when subpaths are provided.
• Use cp -a -v -- to preserve attributes and robustly copy data.
• Quote and guard rm -rf and path arguments (--) to prevent accidental deletions when variables are empty or contain spaces.
• Keep existing ownership/permission adjustments.

2. grafana/shared/grafana_start.sh

• Quote destructive cleanup targets:
  • rm -f -- "$f"/*
  • rm -rf -- "$f"
• Prevents pathname/globbing issues during cleanup; behavior is unchanged as long as $f points to a valid directory.

3. cron/backup_artificial.sh

• Add strict mode, quote variables, and guard rm/mv/tar targets (--, quotes) to avoid unintended deletions and path issues.
• Keep output, file names, and exit codes identical.

4. util_sh/sort_json.sh

• Add strict mode, create temp file in current directory using mktemp, quote paths, and avoid UUOC.
• Behavior unchanged: stable key-sorted JSON written back atomically.

Reasoning and impact

• Prevents accidental deletions if variables are unset/empty or contain whitespace.
• Avoids subtle failures when destination parent directories do not exist.
• Improves script robustness in automation/CI and container environments.
• No change to intended behavior or outputs.

Files changed

• util_sh/db_data_mv.sh
• grafana/shared/grafana_start.sh
• cron/backup_artificial.sh
• util_sh/sort_json.sh