Add haptic feedback when crossing media message boundaries

[dasmfm]

Summary

• Adds a light selection haptic when swiping in the gallery from one media message/group to another.
• Treats grouped media albums as one boundary using groupInfo.stableId.
• Initializes the current boundary on gallery open so the first boundary transition also triggers feedback.

Behavior

• No haptic when moving between items in the same media group.
• Haptic when moving from one group/message to another, including single-image messages.

Testing

• Tested on simulator with temporary on-screen debug indication at the same trigger point, since simulator does not produce physical haptic feedback.
• Verified the indication appears only when moving to a different media message/group, and not when moving within the same media group.