refactor: wwitch virtualhid_control to SDL3 + ImGui

[ReenigneArcher]

Replaces the Windows-native diagnostic UI with an SDL3/Dear ImGui implementation and unifies the tool frontend stack across platforms. The build now vendors CPM.cmake, adds a repository package lock for SDL3 and ImGui, and introduces LIBVIRTUALHID_TOOLS_STATIC_SDL3 (default) to prefer static SDL3 linkage when available. Documentation was updated to reflect the new UI architecture and toolchain behavior.

Description

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

[codecov]

Codecov Report

❌ Patch coverage is 0% with 495 lines in your changes missing coverage. Please review.
✅ Project coverage is 76.64%. Comparing base (4715020) to head (a16474e).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
tools/virtualhid_control.cpp	0.00%	352 Missing and 143 partials ⚠️

Additional details and impacted files

@@ Coverage Diff @@## master #45 +/- ##
==========================================
+ Coverage 76.17% 76.64% +0.47% 
==========================================
Files 18 18 Lines 5188 5156 -32 Branches 1987 2039 +52 ==========================================
Hits 3952 3952 + Misses 1105 816 -289 - Partials 131 388 +257 

Flag	Coverage Δ
Linux-Clang	55.83% <0.00%> (-10.14%)	⬇️
Linux-GCC	68.65% <0.00%> (-12.38%)	⬇️
Windows-MSVC	90.77% <ø> (ø)
Windows-MinGW-UCRT64	64.45% <0.00%> (+1.06%)	⬆️
macOS	50.62% <0.00%> (-13.76%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
tools/virtualhid_control.cpp	0.00% <0.00%> (ø)

... and 7 files with indirect coverage changes

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[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