Fix foundry install target missing commit pin

[ramGit22]

Summary

• Defaulted the FOUNDRY_COMMIT variable so make install-foundry always pins Foundry to the documented revision, preventing empty-argument failures when the variable is unset.

Testing

✅ make -n install-foundry

[cb-heimdall]

✅ Heimdall Review Status

Requirement	Status	More Info
Reviews	✅ 2/2	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 2 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 2 2 1 if commit is unverified 0 Sum 2