add: pairwise elo voting workflow

README.md

@@ -61,6 +61,10 @@ npm run build:thumbs:force
 `data/elo.json` stores the seed rating, Elo `kFactor`, and a win-loss record for each meal.
 The page build keeps this file aligned with `data/meals.json`, so new meals automatically appear in `rankings.html` with the default seed rating.
 
+The interactive voting flow on `rankings.html` uses browser `localStorage` for persistence.
+That means Elo votes persist across reloads on the same browser and device, but they do not sync automatically across devices.
+Use the reset button on the rankings page if you want to clear the local vote history and go back to the seeded board.
+
 ## Image Conventions
 
 - Full-size images and thumbnails share the same numeric ID
@@ -94,5 +98,5 @@ The `x` and `y` values are normalized from `0` to `1`, where `0.5, 0.5` is the c
 
 ## Planned Features
 
-1. A pairwise voting page that shows two food images at a time and updates Elo rankings based on the selected winner.
+1. Optional shared sync or export/import for rankings if browser-local persistence becomes too limiting.
 2. General cleanup and history cleanup once the bigger structural changes are in place.