Add sync error logging, extend error flash, fix unload saves

- Log workforce sync errors to backend stdout so they appear in docker logs
- Extend error flash from 5s to 15s so errors are readable
- Replace sendBeacon (POST-only) with keepalive fetch (PUT) on unload —
  sendBeacon was hitting 404s on all three unload saves

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/node_modules/ajv/dist/compile/rules.js

@@ -0,0 +1,26 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.getRules = exports.isJSONType = void 0;
+const _jsonTypes = ["string", "number", "integer", "boolean", "null", "object", "array"];
+const jsonTypes = new Set(_jsonTypes);
+function isJSONType(x) {
+    return typeof x == "string" && jsonTypes.has(x);
+}
+exports.isJSONType = isJSONType;
+function getRules() {
+    const groups = {
+        number: { type: "number", rules: [] },
+        string: { type: "string", rules: [] },
+        array: { type: "array", rules: [] },
+        object: { type: "object", rules: [] },
+    };
+    return {
+        types: { ...groups, integer: true, boolean: true, null: true },
+        rules: [{ rules: [] }, groups.number, groups.string, groups.array, groups.object],
+        post: { rules: [] },
+        all: {},
+        keywords: {},
+    };
+}
+exports.getRules = getRules;
+//# sourceMappingURL=rules.js.map