feat: Cards writings and balancing (M8)

tools/bal-edit.mjs

@@ -0,0 +1,15 @@
+// Edits balance.json from the command line and keeps its compact layout.
+//   node tools/bal-edit.mjs path=value [path=value ...]      e.g. gain=2.8 debt.premiumCoef=0.0008
+import fs from "node:fs";
+import { format } from "./cardfmt.mjs";
+
+const p = new URL("../web/data/balance.json", import.meta.url);
+const j = JSON.parse(fs.readFileSync(p, "utf8"));
+for (const a of process.argv.slice(2)) {
+  const [path, val] = a.split("=");
+  const keys = path.split(".");
+  let o = j;
+  for (const k of keys.slice(0, -1)) o = o[k] ??= {};
+  o[keys.at(-1)] = JSON.parse(val);
+}
+fs.writeFileSync(p, `${format(j)}\n`);