feat(viewer): add pinch-to-zoom for photos on Android

Add pinch/pan/double-tap zoom to the full-screen photo viewer, mirroring the
web viewer semantics:

- scale is a multiplier of the natural size, capped at 200%; the fitted view
  is the lower bound
- double tap toggles fitted view <-> 100% natural anchored at the tap
- the original loads on zoom, with the preview kept as a placeholder so
  entering zoom never flashes a black surface
- the pager is disabled while zoomed (drags pan the image) and the zoom resets
  when leaving a photo
- video and 360 panoramas are unaffected

Implement PhotoZoom (zoom math) and ZoomableImage (gestures), wire it into
ViewerContent/MediaPage, and cover it with unit, Compose and device tests.

OpenSpec change: add-mobile-photo-zoom

This commit is contained in:

2026-10-13 12:30:49 +03:00

parent 43f5520236

commit f6df9e23f2

14 changed files with 949 additions and 10 deletions

									
										openspec/changes/add-mobile-photo-zoom/.openspec.yaml
									
		+2
		
												View File
												
				@@ -0,0 +1,2 @@

				schema: spec-driven

				created: 2026-10-13