Fixes 3.0 install not actually installing anything

[gulliverhan]

Summary

without this you get this issue where nothing actually happens on install
~/Repos/site$ ~/agent-os/scripts/project-install.sh

=== Agent OS Project Installation ===

The issue was a bash quirk:
((chain_depth++)) - post-increment returns the OLD value (0), which bash treats as "false" → exit code 1
((++chain_depth)) - pre-increment returns the NEW value (1), which bash treats as "true" → exit code 0
With set -e enabled, the script was dying on that line.

Configuration:

Linked item

• Implements: Fresh install triggers no actual install #311

Checklist

• [x ] Linked to related Issue/Discussion
• Documented steps to test (below)
• Drafted “how to use” docs (if this adds new behavior)
• Backwards compatibility considered (notes if applicable)

Documented steps to test

1. install new project
2. with this change it installs agent-os

Notes for reviewers

thanks for all your great work