fix: format hour display on Loop End screen to avoid floating-point precision errors

- Use formatHour() instead of raw {hour} to display time in HH:MM format
  (e.g. '15:00' instead of '14.999999999999998')
- Export formatHour from stores barrel index
- Fixes #336

docs/dependency-graph.json

@@ -1,6 +1,6 @@
 {
   "_meta": {
-    "generated": "2026-06-10T07:56:29.402Z",
+    "generated": "2026-06-10T08:00:17.492Z",
     "description": "Import dependency graph for src/lib/game. Keys are files, values are arrays of files they import.",
     "usage": "To find what a file affects, search for its path in the VALUES. To find what a file depends on, look at its KEY entry."
   },