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/minimatch/dist/esm/ast.d.ts

@@ -0,0 +1,22 @@
+import type { MinimatchOptions, MMRegExp } from './index.js';
+export type ExtglobType = '!' | '?' | '+' | '*' | '@';
+export declare class AST {
+    #private;
+    type: ExtglobType | null;
+    id: number;
+    get depth(): number;
+    constructor(type: ExtglobType | null, parent?: AST, options?: MinimatchOptions);
+    get hasMagic(): boolean | undefined;
+    toString(): string;
+    push(...parts: (string | AST)[]): void;
+    toJSON(): unknown[];
+    isStart(): boolean;
+    isEnd(): boolean;
+    copyIn(part: AST | string): void;
+    clone(parent: AST): AST;
+    static fromGlob(pattern: string, options?: MinimatchOptions): AST;
+    toMMPattern(): MMRegExp | string;
+    get options(): MinimatchOptions;
+    toRegExpSource(allowDot?: boolean): [re: string, body: string, hasMagic: boolean, uflag: boolean];
+}
+//# sourceMappingURL=ast.d.ts.map