Add --open flag to /insights to auto-open report in browser

Feature Request

After running /insights, the report HTML file path is printed but the user has to manually open it. It would be nice to have a flag like --open or -o that automatically opens the generated report in the default browser.

Current behavior:
/insights generates the report and prints the file path. User must manually run open <path> (macOS) or equivalent.

Desired behavior:
/insights --open (or /insights -o) generates the report AND opens it in the default browser automatically.

This is a small quality-of-life improvement — the report is always meant to be viewed in a browser, so having a one-step command makes sense.

🤖 Generated with Claude Code