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-regex/index.js

@@ -0,0 +1,12 @@
+// TODO! cut this down? do we need the onlyFirst option?
+export const ansiRegex = ({ onlyFirst = false } = {}) => {
+    // Valid string terminator sequences are BEL, ESC\, and 0x9c
+    const ST = "(?:\\u0007|\\u001B\\u005C|\\u009C)";
+    // OSC sequences only: ESC ] ... ST (non-greedy until the first ST)
+    const osc = `(?:\\u001B\\][\\s\\S]*?${ST})`;
+    // CSI and related: ESC/C1, optional intermediates, optional params (supports ; and :) then final byte
+    const csi = "[\\u001B\\u009B][[\\]()#;?]*(?:\\d{1,4}(?:[;:]\\d{0,4})*)?[\\dA-PR-TZcf-nq-uy=><~]";
+    const pattern = `${osc}|${csi}`;
+    return new RegExp(pattern, onlyFirst ? undefined : "g");
+};
+//# sourceMappingURL=index.js.map