chore: unify README under Smoo AI brand and voice

[brentrager]

Rebrands the README to the unified Smoo AI brand spec: branded header (logo + name + tagline + flat-square brand-color badges), brand voice, "Part of Smoo AI" section, and consistent footer line.

All real technical content is preserved — install commands, CLI quick start, the full CLI command reference (auth, runs, cases, environments, deployments), JSON output, CI/CD usage with the GitHub Actions example, development commands, and the MIT license. Purely a restructure + rephrase for brand consistency.

No docs/ vault in this repo, so nothing else changed.

🤖 Generated with Claude Code

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Latest commit: e7518e6

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