pathways: spatial movement, bigger tiles, cleaner exits

- movement lands on the photo already occupying the cell ahead instead
  of skipping over it to place a new one; new photos only fill genuinely
  empty cells, and already-placed path targets still jump to their tile
- tiles 360px desktop / 200px mobile
- fix hover exits being clipped half-off by the tile's overflow:hidden
  (clip now lives on the img only); restyle as white circle buttons with
  SVG chevrons and pill path labels

1 files changed, 5 insertions, 4 deletions

diff --git a/README.md b/README.md
index 8a0496b..31c6e94 100644
--- a/README.md
+++ b/README.md
@@ -23,10 +23,11 @@ stays behind basic auth at <https://prism.dax.ist>; pathways is public.
 - Each path is an ordered cycle (by taken date, then id): walking "grey" goes
   grey → grey → … and wraps around. Assignment is deterministic, so revisiting
   a photo always offers the same four exits.
-- If a step lands on a photo already placed in the mosaic, focus just jumps to
-  its existing tile — the mosaic never holds two copies. If it lands on a grid
-  cell already occupied by a *different* photo, the new photo keeps stepping in
-  that direction until it finds a free cell, so nothing is ever covered up.
+- Movement is spatial: pressing a direction lands you on whatever photo already
+  occupies that cell — you walk through photos you've placed before rather than
+  over them. New photos are only added when you step into a genuinely empty
+  cell. If the path's next photo is already placed elsewhere, focus jumps to
+  it, so the mosaic never holds two copies of a photo.
 
 ## Run it