feat: support multiple files in --file flag

[pixincreate]

Summary

• Allow multiple --file flags or comma-separated paths in a single command
• Example: key-watch --file a.txt --file b.txt or key-watch --file a.txt,b.txt

Changes

• src/cli.rs: Changed file: Option<String> to file: Vec<String> with value_delimiter = ','
• src/scanner.rs: Updated to extend target_paths from the vec instead of single option
• tests/scanner_tests.rs: Added test_multiple_files_scan test
• Fixed existing tests to use vec![] instead of None

Closes

Closes #15

[Copilot]

Pull request overview

This PR updates KeyWatch’s CLI and scan pipeline to accept multiple file targets through --file, aligning the scanner with issue #15’s request to scan more than one file in a single invocation.

Changes:

• Changes CliOptions.file from a single optional path to a vector with comma-delimited parsing support.
• Updates run_scan to add all provided file paths to the scan target list.
• Refreshes scanner/hook tests and adds a multi-file scan test.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
src/cli.rs	Expands the --file CLI option to accept multiple values and comma-separated input.
src/scanner.rs	Switches scan target collection from a single file path to all provided file paths.
tests/scanner_tests.rs	Updates scanner tests for the new Vec<String> shape and adds a multi-file scan case.
tests/hooks_tests.rs	Adjusts hook tests to construct CliOptions with an empty file list.