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/commonjs/string-width/index.js

@@ -0,0 +1,49 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.stringWidth = stringWidth;
+const index_js_1 = require("../strip-ansi/index.js");
+const index_js_2 = require("../eastasianwidth/index.js");
+const index_js_3 = require("../emoji-regex/index.js");
+function stringWidth(str, options = {}) {
+    if (typeof str !== "string" || str.length === 0) {
+        return 0;
+    }
+    options = {
+        ambiguousIsNarrow: true,
+        ...options,
+    };
+    str = (0, index_js_1.stripAnsi)(str);
+    if (str.length === 0) {
+        return 0;
+    }
+    str = str.replace((0, index_js_3.emojiRegex)(), "  ");
+    const ambiguousCharacterWidth = options.ambiguousIsNarrow ? 1 : 2;
+    let width = 0;
+    for (const character of str) {
+        const codePoint = character.codePointAt(0);
+        // Ignore control characters
+        if (!codePoint ||
+            codePoint <= 0x1f ||
+            (codePoint >= 0x7f && codePoint <= 0x9f)) {
+            continue;
+        }
+        // Ignore combining characters
+        if (codePoint >= 0x300 && codePoint <= 0x36f) {
+            continue;
+        }
+        const code = (0, index_js_2.eastAsianWidth)(character);
+        switch (code) {
+            case "F":
+            case "W":
+                width += 2;
+                break;
+            case "A":
+                width += ambiguousCharacterWidth;
+                break;
+            default:
+                width += 1;
+        }
+    }
+    return width;
+}
+//# sourceMappingURL=index.js.map