Spec Kit Extensions repo — incubate/test experimental commands

[harikrishnan83]

Hello Spec Kit maintainers & community 👋

While my /cross-feature command is under review (PR #723), I have created an experimental repo to incubate and share extensions before they’re upstreamed.

Repo: https://github.com/polarizertech/spec-kit-extensions

What it is

• Opt-in commands prefixed /specify.extn. to distinguish experiments from first-class commands.
• Lightweight installer that simply adds files to your repo (easy to revert) on top of standard Spec Kit install.

What’s included now

• /specify.extn.cross-feature — analyzes interactions across features using simple Systems-Thinking heuristics and outputs a short report.

Looking for feedback on naming, flags/output, installer DX, and whether /cross-feature (or other ideas) should be proposed for upstreaming.