🧹 Refactor overly long native_screen_content_hash function

[undivisible]

🎯 What: The Windows-specific code inside the native_screen_content_hash function in src/lib.rs was extracted into a new module file, src/windows_capture.rs.
💡 Why: The function was overly long (104 lines), largely due to the Windows API calls for screen capture. This refactoring improves maintainability by segregating OS-specific logic into separate files, mirroring existing patterns (e.g., linux_input.rs, macos_capture.rs).
✅ Verification: Verified by compiling the project with cargo check, formatting the code with cargo fmt, and successfully running the test suite with cargo test --lib.
✨ Result: A more readable src/lib.rs file and better isolated platform-specific logic.

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PR created automatically by Jules for task 16484026348671401474 started by @undivisible

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Note

Low Risk
Behavior-preserving refactor of Windows screen hashing with no API or protocol changes.

Overview
Moves the Windows GDI virtual-screen capture and SHA-256 hashing logic out of native_screen_content_hash in lib.rs into a new windows_capture module, which lib.rs now calls on Windows builds.

This is a structural change only—the capture dimensions, pixel read path, and hash inputs (origin, size, pixel buffer) stay the same, aligning Windows with how Linux and macOS keep platform code in dedicated files.

Also fixes indentation in a CLI integration test helper.

^{Reviewed by Cursor Bugbot for commit a03b89f. Configure here.}

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