Stack Dependencies Autoinclude Merge

stack-dependencies: autoinclude merges like a regular include

A generated unit autoinclude (terragrunt.autoinclude.hcl) now merges into the unit's config using the same default merge as a regular include, which is a shallow merge, applied uniformly across generation, full parse, and discovery. Top-level keys from the unit and the autoinclude combine, and on a conflict the autoinclude wins and replaces the unit's value rather than deep-merging nested maps; locals stay local in scope.

A generated stack autoinclude (terragrunt.autoinclude.stack.hcl) injects unit and stack blocks into the generated terragrunt.stack.hcl. An injected block whose name matches an existing unit or stack now overrides that block wholesale, consistent with unit autoinclude override semantics, and an injected block with a new name is added. This applies uniformly across generation, full parse, and discovery, so a name match no longer produces a duplicate-name error. A stack autoinclude may not declare a top-level dependency block (stacks have no dependencies; declare the dependency inside the target unit's own autoinclude).

A dependency block injected through an autoinclude is now available before a unit's remote_state is evaluated, so referencing dependency.<name>.outputs.<key> there no longer fails. remote_state now behaves the same as generate blocks.