[KazuCocoa]

Summary

Make non-global drivers usable independently while retaining explicit global-driver usage (Appium::Driver.new(opts, true)) and implicit promotion through $driver. The default remains non-global; this PR does not remove global support.

Compatibility notes

• Driver.new(opts) now honors symbol/string global_driver options when the second argument is omitted or nil. Previously, omitting the second argument ignored the hash option. A hash value of true can therefore replace $driver and quit the previous global session. An explicit true/false second argument takes precedence.
• start_driver quits only the receiving wrapper's previous session, instead of quitting an unrelated $driver session. Callers relying on that cross-driver cleanup must quit the other driver explicitly.
• Coordinate conversion and Android inspection use the receiving driver rather than an unrelated $driver. Pass an explicit driver to px_to_window_rel when a different session is intended.
• Re-promoting singleton Appium methods refreshes generated wrappers to use the newly supplied driver instead of retaining an earlier driver.

Validation

• Unit tests: 43 tests, 100 assertions passed.
• Local Android functional tests: both global-driver modes passed (100 tests, 150 assertions each).
• Local changed iOS tests on iOS 26.5: both modes passed (36 tests, 77 assertions each).
• RuboCop passed.
• Latest CI on db255c5 still has functional failures in both modes: Android swipe navigation (1 error per mode); iOS swipe and touch-and-hold (2 errors per mode). Full CI is not yet green.

Release notes

The override below supplies explicit changelog entries to Release Please. Use squash merge; Release Please does not support this override with plain merge commits.

BEGIN_COMMIT_OVERRIDE
feat: support independent non-global drivers while preserving explicit global-driver usage and the existing non-global default

fix: honor symbol and string global_driver hash options when the constructor's second argument is omitted or nil; true now replaces the global driver and quits its previous session, while an explicit boolean argument takes precedence

fix: make start_driver quit only its own previous session; callers relying on cleanup of another global driver must quit that driver explicitly

fix: use the receiving driver's session for coordinate conversion and Android inspection instead of an unrelated global driver

fix: refresh generated singleton methods on re-promotion so they use the newly supplied driver rather than the previous driver

fix: clear session and app-string cache on quit and reload app strings for replacement sessions
END_COMMIT_OVERRIDE