fix(compiler): expose MATCH in include vars evaluation

[SergioChan]

Summary

• make MATCH available before evaluating include-level vars so wildcard include namespaces can reference {{index .MATCH 0}}
• preserve existing variable merge order by only pre-seeding MATCH early (other call vars remain applied in the existing step)
• add a regression test for wildcard include vars (stack:*) proving ENV is resolved from the namespace match

Testing

• go test ./... -run TestIncludeWildcardVarsExposeMatch (cannot run in this environment because this repo requires Go 1.25 and the toolchain download is unavailable here)
• validation provided via focused regression test at TestIncludeWildcardVarsExposeMatch

Related

Fixes #2732