Add screenshots and demo GIF

[sugarpoo]

Add public-safe visual assets for the README and launch docs.

Suggested assets:

• terminal install screenshot
• fake learning candidate screenshot
• maintenance report screenshot
• short demo GIF following docs/demo.md

Acceptance criteria:

• No private logs, real reports, backups, state files, personal notes, credentials, or personal paths are visible.
• Assets are added under assets/.
• README or docs link to the assets where useful.