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/@isaacs/cliui/dist/esm/ansi-styles/index.d.ts

@@ -0,0 +1,34 @@
+export declare const modifierNames: string[];
+export declare const foregroundColorNames: string[];
+export declare const backgroundColorNames: string[];
+export declare const colorNames: string[];
+export declare const codes: Map<number, number>;
+export declare const ansiStyles: {
+    [x: string]: unknown;
+    codes: Map<number, number>;
+    modifier: {
+        [k: string]: {
+            open: string;
+            close: string;
+        };
+    };
+    color: {
+        close: string;
+        ansi: (code: number) => string;
+        ansi256: (code: number) => string;
+        ansi16m: (red: number, green: number, blue: number) => string;
+    };
+    bgColor: {
+        close: string;
+        ansi: (code: number) => string;
+        ansi256: (code: number) => string;
+        ansi16m: (red: number, green: number, blue: number) => string;
+    };
+    rgbToAnsi256(red: number, green: number, blue: number): number;
+    hexToRgb(hex: number): [number, number, number];
+    hexToAnsi256(hex: number): number;
+    ansi256ToAnsi(code: number): number;
+    rgbToAnsi(red: number, green: number, blue: number): number;
+    hexToAnsi(hex: number): number;
+};
+//# sourceMappingURL=index.d.ts.map