Enable admins and directors to send invoices via webhook

Introduce a new backend route `/api/reconciliation/send-invoice-webhook` to proxy invoice data to external webhooks, converting files to base64 and handling CORS issues.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 1e4433b5-47ab-464c-b663-fea2e53367dd
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Event-Id: 6f3c3694-5a67-4b47-b27c-af49da7ad447
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/1957c339-2757-4d1f-8e92-e9f71a1ce58e/1e4433b5-47ab-464c-b663-fea2e53367dd/LXHtbOp

package-lock.json

@@ -41,6 +41,7 @@
         "@radix-ui/react-tooltip": "^1.2.0",
         "@tanstack/react-query": "^5.60.5",
         "@types/bcrypt": "^6.0.0",
+        "@types/form-data": "^2.2.1",
         "@types/memoizee": "^0.4.12",
         "@types/node-fetch": "^2.6.13",
         "@types/pg": "^8.15.4",
@@ -58,6 +59,7 @@
         "express": "^4.21.2",
         "express-rate-limit": "^7.5.1",
         "express-session": "^1.18.1",
+        "form-data": "^4.0.4",
         "framer-motion": "^11.13.1",
         "iconv-lite": "^0.6.3",
         "input-otp": "^1.4.2",
@@ -3750,6 +3752,15 @@
         "@types/express": "*"
       }
     },
+    "node_modules/@types/form-data": {
+      "version": "2.2.1",
+      "resolved": "https://registry.npmjs.org/@types/form-data/-/form-data-2.2.1.tgz",
+      "integrity": "sha512-JAMFhOaHIciYVh8fb5/83nmuO/AHwmto+Hq7a9y8FzLDcC1KCU344XDOMEmahnrTFlHjgh4L0WJFczNIX2GxnQ==",
+      "license": "MIT",
+      "dependencies": {
+        "@types/node": "*"
+      }
+    },
     "node_modules/@types/http-errors": {
       "version": "2.0.5",
       "resolved": "https://registry.npmjs.org/@types/http-errors/-/http-errors-2.0.5.tgz",