Remove broken ASCII logos from install script and README

[benjaminLedel]

The ASCII art doesn't render correctly without the TUI shadow markers. Keep the SVG logo in README, use a simple success message in install.

https://claude.ai/code/session_01UWUjuKndM7oTveau5hyNU2

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[github-actions]

Hey! Your PR title Remove broken ASCII logos from install script and README doesn't follow conventional commit format.

Please update it to start with one of:

• feat: or feat(scope): new feature
• fix: or fix(scope): bug fix
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