Simplify README and add demo video embed

[h4rm0n1c]

Motivation

• Make the top-level README more concise and approachable by removing dense, GPT-style wording and streamlining setup and usage information.
• Surface a demo video near the top so visitors can quickly preview the project via a YouTube thumbnail link.

Description

• Replace the verbose introduction with a shorter project summary and move screenshots/video thumbnail to the top of README.md.
• Add a linked YouTube thumbnail that points to https://www.youtube.com/watch?v=PFJt_EG5f_c and displays the video preview image.
• Rework headings and bullets for clarity (rename the previous “Highlights” section to Why it exists, condense the Wine automation text, and keep existing commands like make -f Makefile.mingw and ./scripts/winetricks/setup_nettts_prefix.sh intact).

Testing

• No automated tests were run because this is a docs-only change.

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Codex Task