Add version command with goreleaser integration

[Copilot]

Adds a version command that displays version information based on build context: clean output for tagged releases, detailed snapshot info for development builds.

Changes

• cmd/version.go: New command with variables (version, commit, date) injected via ldflags at build time
• .goreleaser.yaml: Configured ldflags to inject {{.Version}}, {{.Commit}}, {{.Date}} template variables
• cmd/version_test.go: Test coverage for tagged releases, snapshots, and dev builds

Behavior

# Tagged release
$ semvertool version
semvertool v1.2.3

# Snapshot build (non-tagged commit)
$ semvertool version
semvertool v0.0.0-next (snapshot)
  commit: abc123def456
  built:  2025-02-14T10:30:00Z

# Local dev build (no ldflags)
$ semvertool version
semvertool dev (snapshot)
  commit: none
  built:  unknown

Command logic branches on whether version == "dev" (local build) or commit is populated (goreleaser snapshot) to determine output format.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add version command</issue_title>
<issue_description></issue_description>

<agent_instructions>Create a version command that prints the current version of the tool. If it is a tagged version it should return the tag, if was not built from a tag it should include information that it is a snapshot and info about the commit. Use the information generated by goreleaser for the tag information</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Add version command #10

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