refactor: use Go native build info for commit and date

[fank]

Summary

• Replace ldflags injection of commit and date with runtime/debug.ReadBuildInfo() which Go embeds automatically from VCS
• Remove BuildInfo struct — version is now passed as a string, commit/date derived from runtime/debug
• Only version remains as an ldflag (no native way to get the git tag at runtime)
• Aligns the build pattern across all three CLIs (esq, atl, n8nctl) to use identical ldflags: -X main.version={{.Version}}

Test plan

• go vet ./... passes
• go test ./... passes (all existing tests unaffected)
• Local build shows correct commit hash and build date from VCS
• Version injection via ldflag still works
• -s -w stripping does NOT affect runtime/debug build info

[gemini-code-assist]

Code Review

This pull request refactors the CLI to dynamically retrieve VCS information (commit hash and build date) using the runtime/debug package instead of relying on ldflags during the build process. The BuildInfo struct has been removed, and a new vcsInfo function extracts metadata directly from the binary's build information. Feedback was provided to enhance the vcsInfo function by checking the vcs.modified flag to indicate whether the binary was built from a 'dirty' repository state.

[github-actions]

Merging this branch will not change overall coverage

Impacted Packages	Coverage Δ	🤖
github.com/enthus-appdev/atl-cli/cmd/atl	0.00% (ø)
github.com/enthus-appdev/atl-cli/internal/cmd	0.00% (ø)

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Coverage by file

Changed files (no unit tests)

Changed File	Coverage Δ	Total	Covered	Missed	🤖
github.com/enthus-appdev/atl-cli/cmd/atl/main.go	0.00% (ø)	3 (-1)	0	3 (-1)
github.com/enthus-appdev/atl-cli/internal/cmd/root.go	0.00% (ø)	46 (+16)	0	46 (+16)

Please note that the "Total", "Covered", and "Missed" counts above refer to code statements instead of lines of code. The value in brackets refers to the test coverage of that file in the old version of the code.