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/standalone/instance.js

@@ -0,0 +1,35 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+const core_1 = require("../core");
+const _1 = require(".");
+const requireFromString = require("require-from-string");
+class AjvPack {
+    constructor(ajv) {
+        this.ajv = ajv;
+    }
+    validate(schemaKeyRef, data) {
+        return core_1.default.prototype.validate.call(this, schemaKeyRef, data);
+    }
+    compile(schema, meta) {
+        return this.getStandalone(this.ajv.compile(schema, meta));
+    }
+    getSchema(keyRef) {
+        const v = this.ajv.getSchema(keyRef);
+        if (!v)
+            return undefined;
+        return this.getStandalone(v);
+    }
+    getStandalone(v) {
+        return requireFromString((0, _1.default)(this.ajv, v));
+    }
+    addSchema(...args) {
+        this.ajv.addSchema.call(this.ajv, ...args);
+        return this;
+    }
+    addKeyword(...args) {
+        this.ajv.addKeyword.call(this.ajv, ...args);
+        return this;
+    }
+}
+exports.default = AjvPack;
+//# sourceMappingURL=instance.js.map