GRM-20: refactor: rework all scripts to use click and i18n

- Replace argparse/print/sys.exit with click commands and ClickException
- Translate all user-facing messages via _()
- Add friendly Oops! / Nice! prompts
- Wrap HTTP errors in all scripts with user-friendly translated messages
- Update all unit tests to use CliRunner and expect ClickException
- Add 100% branch coverage for new HTTP error handling branches
- Add missing translation keys to i18n.py
- Fix pre-commit hook to use venv Python for validate_commit_msg.py

.pre-commit-config.yaml

@@ -3,7 +3,7 @@ repos:
     hooks:
       - id: validate-commit-msg
         name: validate commit message
-        entry: python3 scripts/validate_commit_msg.py
+        entry: .venv/bin/python scripts/validate_commit_msg.py
         language: system
         stages: [commit-msg]
         pass_filenames: true