Add golden CLI help integration test

[cduggn]

Motivation

• Provide a stable, easy-to-update integration test for the CLI by snapshotting the root help output to a golden file.
• Protect against accidental formatting or output regressions in the help/usage text including ASCII header art.
• Make it simple to refresh the expected output when intentional changes are made by using an update flag.

Description

• Add cmd/ccexplorer/integration_test.go containing TestCLIHelpGolden which runs cli.RootCommand() and captures its combined stdout/stderr.
• The test compares the command output to the golden fixture at cmd/ccexplorer/testdata/help.golden and supports regenerating it with the -update flag.
• Add the initial golden fixture at cmd/ccexplorer/testdata/help.golden containing the expected CLI help output.

Testing

• Ran go test ./cmd/ccexplorer -run TestCLIHelpGolden -update to generate the golden file, which completed successfully.
• Ran go test ./cmd/ccexplorer -run TestCLIHelpGolden to validate the test against the committed golden file, which passed.

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Codex Task