Bump install.sh / install.ps1 pin to unsloth>=2026.8.8

[danielhanchen]

Summary

• PyPI release unsloth 2026.8.8 is now live.
• Bumps the pinned unsloth floor in install.sh and install.ps1 from unsloth>=2026.8.7 to unsloth>=2026.8.8 so fresh installs resolve to the new wheel.
• Updates all 5 install commands in each of install.sh and install.ps1 (migrated no-torch / migrated / no-torch / local / auto torch backend paths).
• unsloth-zoo>=2026.8.5 is left as is: 2026.8.5 is still the current PyPI release and matches the unsloth_zoo>=2026.8.5 floor in pyproject.toml.
• Tagged on main as v0.1.525-beta.

Follows the same pattern as #5716.

Test plan

• Sanity-run install.sh on a clean Linux host
• Sanity-run install.ps1 on a clean Windows host
• Confirm uv pip install "unsloth>=2026.8.8" resolves cleanly

bash -n install.sh and a PowerShell parser pass over install.ps1 both succeed.

[chatgpt-codex-connector]

Codex usage limits have been reached for code reviews. Please check with the admins of this repo to increase the limits by adding credits.
Repo admins can enable using credits for code reviews in their settings.