Use actual output directory in CLI completion message

[Copilot]

The CLI completion message after report generation always showed hardcoded paths (streamlit_report/sections, quarto_report) regardless of the --output_directory flag, making the message misleading when a custom output path was specified.

Changes

• src/vuegen/utils/__init__.py — Added output_dir parameter to get_completion_message. When provided, all displayed paths are derived from it; falls back to previous defaults when None (backward compatible).
• src/vuegen/__main__.py — Captures report_dir from get_report() (previously discarded as _, _) and passes it as output_dir to get_completion_message.

Example

With --output_directory /custom/path, the message now reflects the real location:

📂 All scripts to build the Streamlit app are available at:
    /custom/path/streamlit_report/sections

▶️ To run the Streamlit app, use the following command:
    streamlit run /custom/path/streamlit_report/sections/report_manager.py