feat: Sprint 1 — staffing assign, dashboard cache, bulk ops, notifications

Staffing "Assign" Button:
- Inline assignment form on each suggestion card in StaffingPanel
- Pre-fills project, dates, hours from search criteria
- 1-click confirm creates allocation with PROPOSED status
- Success/error toasts, removes assigned suggestions from list

Dashboard Redis Caching:
- New cache utility (packages/api/src/lib/cache.ts) with get/set/invalidate
- All 5 dashboard queries wrapped with 60s TTL cache-aside pattern
- Auto-invalidation on allocation + project mutations (fire-and-forget)
- Graceful fallthrough to DB if Redis unavailable

Bulk Operations:
- CSV export for selected resources and projects (apps/web/src/lib/csv-export.ts)
- Project batch delete mutation with cascade (assignments, demands, rules)
- Export/Delete buttons added to BatchActionBar on both list pages

Budget Overrun Notifications:
- checkBudgetThresholds() alerts at 80% (HIGH) and 100% (URGENT)
- Called after every allocation mutation, duplicate-safe
- Targets ADMIN + MANAGER users with SSE delivery

Estimate Approval Reminders:
- checkPendingEstimateReminders() finds SUBMITTED versions > 3 days old
- Cron endpoint: GET /api/cron/estimate-reminders (optional CRON_SECRET auth)
- Creates in-app REMINDER notifications, duplicate-safe

Co-Authored-By: claude-flow <ruv@ruv.net>

apps/web/src/lib/csv-export.ts

@@ -0,0 +1,39 @@
+/**
+ * Generic CSV export utility.
+ * Generates a CSV string from an array of objects and triggers a download.
+ */
+
+function escapeCsvValue(value: unknown): string {
+  if (value == null) return "";
+  const str = String(value);
+  // Wrap in quotes if it contains comma, quote, or newline
+  if (str.includes(",") || str.includes('"') || str.includes("\n")) {
+    return `"${str.replace(/"/g, '""')}"`;
+  }
+  return str;
+}
+
+interface CsvColumn<T> {
+  header: string;
+  accessor: (row: T) => unknown;
+}
+
+export function generateCsv<T>(rows: T[], columns: CsvColumn<T>[]): string {
+  const header = columns.map((c) => escapeCsvValue(c.header)).join(",");
+  const body = rows
+    .map((row) => columns.map((col) => escapeCsvValue(col.accessor(row))).join(","))
+    .join("\n");
+  return `${header}\n${body}`;
+}
+
+export function downloadCsv(csvContent: string, filename: string): void {
+  const blob = new Blob(["\uFEFF" + csvContent], { type: "text/csv;charset=utf-8;" });
+  const url = URL.createObjectURL(blob);
+  const link = document.createElement("a");
+  link.href = url;
+  link.download = filename;
+  document.body.appendChild(link);
+  link.click();
+  document.body.removeChild(link);
+  URL.revokeObjectURL(url);
+}