ci: add more pytest files and update cli to download root

[hali-coding]

Changes

• Update pytest cases
• Update cli command with new getroot subcommand

[Copilot]

Pull request overview

This PR extends the ssltui CLI with a new getroot subcommand for exporting the root CA certificate, and adds a broad set of end-to-end pytest coverage for CLI, TUI (tmux-driven), and REST API behavior.

Changes:

• Add ssltui getroot CLI subcommand with optional --out file output.
• Add smoke, TUI lifecycle/init, API serve, and getroot CLI end-to-end tests.
• Document the new getroot usage in the README.

Reviewed changes

Copilot reviewed 4 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
ssltui/__main__.py	Adds getroot subcommand wiring and implementation.
README.md	Documents getroot command usage and intent (stdout PEM, stderr summary).
tests/test_1_smoke.py	Adds basic import/config/CLI help smoke coverage.
tests/test_2_tui_init.py	Adds tmux-driven CA init end-to-end test.
tests/test_3_tui_cert_lifecycle.py	Adds tmux-driven issue → save → revoke lifecycle test.
tests/test_4_api_serve.py	Adds end-to-end REST API tests against a real ssltui serve session.
tests/test_5_getroot.py	Adds CLI coverage for getroot stdout, --out, and uninitialised error.

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