Release 1.5.84.0 stable

[akaydev-coder]

What changed

• Promotes 1.5.84.0 to Stable.
• Fixes the inverted F2Selection tweak so "Cycle selection with F2 while renaming" now matches the checkbox state.
• Includes the stabilized 1.5.84 feature set: cursor-loop fallback, per-tab-state text shadows, tab skin geometry helpers/tests, and stable installer metadata.

Validation

• Built QTTabBar Release successfully.
• Built QTTabBarNative x64 Release successfully.
• Built MSI and Bundle installers successfully with WiX 3.14.
• Ran git diff --check / staged diff check successfully.

Notes

• The SDK-style test project still requires Microsoft.NET.Sdk to be installed in the local MSBuild environment before it can be built here.