Various enhancements to the build process

[edwardalee]

This PR makes the following enhancements to the build process:

• Fix compiler warnings.
• Add a lingo update that removes build artifacts, installed dependencies, and lock file, and then rebuilds.
• Print what is being removed when running lingo clean and lingo update
• Print what dependency is being loaded before loading it.

[Copilot]

Pull request overview

This PR enhances the lingo build tool’s developer feedback and cleanup capabilities, primarily around dependency resolution and cleaning build artifacts.

Changes:

• Added a cleanall CLI command and documented it in the README.
• Improved error context for filesystem operations during dependency management and lockfile handling.
• Added more console output around build/dependency steps and cleanup actions.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
src/util/mod.rs	Prints cleanup results when deleting build subdirectories.
src/package/target_properties.rs	Fixes serde key for library artifacts deserialization.
src/package/management.rs	Adds richer context to FS errors and prints dependency-resolution progress/timing.
src/package/lock.rs	Prints lock validation/fetch/checksum timing during init.
src/main.rs	Adds cleanall implementation and related deletion helper.
src/backends/mod.rs	Prints build-step progress during backend dispatch.
src/args.rs	Adds the Cleanall subcommand.
README.md	Updates CLI help text to include cleanall.

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[edwardalee]

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