### Bug Description If the `build-environment` of a part is modified, a rebuild of the part will not be triggered. ### To Reproduce Create a snap with a part declaring a build-environment as so: ``` build-environment: - FOO: bar ``` Build the snap and then modify `bar` to some other value. Rerun the build and notice that the build step for the part is not retriggered. You can also add a key key to `build-environment` such as `- FIZZ: buzz` and no rebuild of the part will be triggered. ### Environment Ubuntu 25.04, building with snapcraft 8.11.1 and LXD latest/edge. ### snapcraft.yaml ```yaml name: test # you probably want to 'snapcraft register <name>' base: core24 # the base snap is the execution environment for this snap version: '0.1' # just for humans, typically '1.2+git' or '1.3.2' # adopt-info: my-part summary: Single-line elevator pitch for your amazing snap # 79 char long summary description: | This is my-snap's description. You have a paragraph or two to tell the most important story about your snap. Keep it under 100 words though, we live in tweetspace and your description wants to look good in the snap store. grade: devel # must be 'stable' to release into candidate/stable channels confinement: devmode # use 'strict' once you have the right plugs and slots parts: my-part: # See 'snapcraft plugins' plugin: nil build-environment: # Run the build, change bar to baz, then rerun the build - FOO: bar # Run the build, add -FIZZ: buzz, then rerun the build - FIZZ: buzz ``` ### Relevant log output ```shell  snapcraft pack --shell Starting snapcraft, version 8.11.1.post53 Logging execution to '/home/dilyn/.local/state/snapcraft/log/snapcraft-20250828-142159.558898.log' Launching managed ubuntu 24.04 instance... Starting instance Starting snapcraft, version 8.11.1.post53 Logging execution to '/tmp/snapcraft.log' Initialising lifecycle Installing build-packages Installing build-snapsc Skipping pull for my-part (already ran) Skipping build for my-part (already ran) Skipping stage for my-part (already ran) Skipping prime for my-part (already ran) Launching shell on build environment... snapcraft-test-amd64-4235994 ../project# cd ../parts/my-part/build/ build environment set for part 'parts' snapcraft-test-amd64-4235994 ../parts/my-part/build# echo $FOO bar snapcraft-test-amd64-4235994 ../parts/my-part/build# echo $FIZZ snapcraft-test-amd64-4235994 ../parts/my-part/build# exit ``` ### Additional context _No response_