Refresh Advisor positioning and README review examples

[kkkiio]

Summary

• Reposition Advisor as a btw-style second opinion and asynchronous watchdog for Pi.
• Rewrite the README with streamlined installation, usage, commands, overlay behavior, and configuration guidance.
• Update the overview image and visual scenario to demonstrate a natural naming review.
• Extend the faux provider and TUI fixture with session-file inspection behavior.
• Refresh package metadata, description, and keywords.

Testing

• Updated the visual test scenario and supporting E2E fixtures for the new README example.
• Full test suite not run (not requested).