refactor(multi-folder-scan): return ExitCode instead of calling process.exit()

[luojiyin1987]

What

Replace 4 process.exit() calls in handleMultiFolderScan with return ExitCode.

This fixes the multi-folder audit-log close path by returning the exit code to the caller, so src/index.ts can close the audit log before exiting.

Why

• Fixes audit-log fd leak: main()'s finally block can now run after multi-folder scans
• Makes handleMultiFolderScan testable without mocking process.exit
• Moves toward consistent exit code handling across the CLI

Changes

• src/scan/multi-folder-scan.ts: Return EXIT_OK / EXIT_FINDINGS instead of calling process.exit(), change return type to Promise<ExitCode>
• src/index.ts: Capture returned exit code and call process.exit() at the call site

Testing

• TypeScript compiles cleanly
• No behavior change (same exit codes, same console output)

Closes #821

[sonukapoor]

Thanks for this - moving process.exit() out of handleMultiFolderScan and into the call site is the right call. It makes the function composable and testable, and the mock change from mockImplementation(() => process.exit(0)) to mockResolvedValue(0) is much cleaner.

Two things before merging: the --fix and --sarif/--cdx unsupported-feature paths return EXIT_FINDINGS (1), but exit code 1 in this codebase means "findings were found above threshold." These paths never evaluate any findings - they bail early because the feature isn't available yet. That's EXIT_ERROR (3) per the contract in src/types.ts. A CI script testing exitCode === 1 would get a false positive here.

The return after process.exit(exitCode) in index.ts is also now unreachable dead code - small cleanup.

Minor: mockResolvedValue(EXIT_OK) would be more intentional than the raw 0, but not a blocker.

[luojiyin1987]

Thanks, fixed.

The unsupported multi-folder --fix / --sarif / --cdx paths now return EXIT_ERROR instead of EXIT_FINDINGS, since they bail out before evaluating findings.

I also removed the unreachable return after process.exit(exitCode), and changed the integration test mock to use EXIT_OK instead of a raw 0.

No new test file was added; I only added coverage to the existing multi-folder scan test file.

[sonukapoor]

This addresses everything - EXIT_ERROR for the unsupported-feature paths is the right call, the dead return is gone, the test mock uses EXIT_OK, and the new handleMultiFolderScan tests cover all the EXIT_ERROR cases cleanly. The audit log close path is now correct too. Nice work.