Compatibility tested across supported Foundry versions

## Summary
Declare a compatibility matrix in `module.json` (e.g. v12 minimum, v13 verified) and verify the module loads and runs core flows on each.

## Motivation
Foundry releases break modules regularly. Without an explicit matrix and verification, "works on my machine" ships.

## Scope
- Pick supported versions (probably current + previous major).
- Manual test pass against each before tagging v0.7.0.
- Document the matrix in module README.

## Acceptance criteria
- [ ] `module.json` declares compatibility range.
- [ ] Manual test log in repo or release notes confirming each version passes the smoke flow.