docs: clarify licensing and macOS backend status

[ReenigneArcher]

Description

Add a root license notice, move the MIT text under LICENSES/, and update install/packaging paths so distributed artifacts still include the expected license files. Refresh README and docs to better describe the current macOS CoreGraphics-only keyboard/mouse backend and keep planned native virtual-HID gamepad support scoped separately.

Screenshot

Issues Fixed or Closed

Roadmap Issues

Type of Change

• feat: New feature (non-breaking change which adds functionality)
• fix: Bug fix (non-breaking change which fixes an issue)
• docs: Documentation only changes
• style: Changes that do not affect the meaning of the code (white-space, formatting, missing semicolons, etc.)
• refactor: Code change that neither fixes a bug nor adds a feature
• perf: Code change that improves performance
• test: Adding missing tests or correcting existing tests
• build: Changes that affect the build system or external dependencies
• ci: Changes to CI configuration files and scripts
• chore: Other changes that don't modify src or test files
• revert: Reverts a previous commit
• BREAKING CHANGE: Introduces a breaking change (can be combined with any type above)

Checklist

• Code follows the style guidelines of this project
• Code has been self-reviewed
• Code has been commented, particularly in hard-to-understand areas
• Code docstring/documentation-blocks for new or existing methods/components have been added or updated
• Unit tests have been added or updated for any new or modified functionality

AI Usage

See our AI usage policy.

• None: No AI tools were used in creating this PR
• Light: AI provided minor assistance (formatting, simple suggestions)
• Moderate: AI helped with code generation or debugging specific parts
• Heavy: AI generated most or all of the code changes

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.70%. Comparing base (485bf6e) to head (7c5c8ed).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #74   +/-   ##
=======================================
  Coverage   74.70%   74.70%           
=======================================
  Files          33       33           
  Lines        7906     7906           
  Branches     2966     2966           
=======================================
  Hits         5906     5906           
- Misses       1720     1722    +2     
+ Partials      280      278    -2     

Flag	Coverage Δ
FreeBSD	50.96% <ø> (ø)
Linux-Clang	56.64% <ø> (ø)
Linux-GCC	67.52% <ø> (ø)
Windows-MSVC	87.90% <ø> (ø)
Windows-MinGW-UCRT64	64.28% <ø> (ø)
macOS	50.28% <ø> (ø)

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see 1 file with indirect coverage changes

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