Generate asset versions during Docker builds

shared/ledger.js

@@ -2,8 +2,8 @@
 // Mirrors manual-roast-planner.html's worksheet box 6 (lines 1-9, totals A/C/D)
 // and box 7 (the four sanity checks) exactly. Imported by both server and browser.
 
-import { parseDuration, parseRangeMidpoint } from "./time.js?v=20260730-release2";
-import { YELLOW_RATIO, SANITY_BANDS } from "./reference-data.js?v=20260730-release2";
+import { parseDuration, parseRangeMidpoint } from "./time.js?v=__ASSET_VERSION__";
+import { YELLOW_RATIO, SANITY_BANDS } from "./reference-data.js?v=__ASSET_VERSION__";
 
 /**
  * @param {import("./fields.js").Plan} plan