The mouse classification helpers checked both the current Button/Action pair and
the deprecated msg.Type / tea.Mouse* constants. Bubble Tea's parser always
populates Button+Action and only DERIVES Type from them, so the Type fallbacks
were pure redundancy (a left-button drag is Action==Motion, already covered by
mouseMotion). Drop them — clears all 11 SA1019 findings in internal/tui with no
behavior change. The left-drag test now asserts the Action==Motion path directly.
Gates: gofmt/vet/build(host+linux+windows)/test -race/staticcheck(SA1019 0)/
deadcode(no new) all pass.
Gnanam
8b7b8296ac