v0.5.1+rpt20250707

ipa: rpi: Fix bug in AfState reporting

A previous change introduced a bug in which it reported AfStateIdle
when idle in Auto mode, when it should continue to report the most
recent AF cycle's outcome (AfStateFocused or AfStateFailed).

Also fix the Pause method so it won't reset state to AfStateIdle
when paused in Continuous AF mode (to match documented behaviour).

Signed-off-by: Nick Hollinghurst <nick.hollinghurst@raspberrypi.com>