Refactor AI chat: streaming, tool calls, UI polish

apps/server/package.json

@@ -47,11 +47,13 @@
     "class-validator": "^0.15.1",
     "echarts": "^6.1.0",
     "exceljs": "^4.4.0",
+    "mammoth": "^1.12.0",
     "multer": "^2.2.0",
     "mysql2": "^3.22.2",
     "passport": "^0.7.0",
     "passport-jwt": "^4.0.1",
     "passport-local": "^1.0.0",
+    "pdf-parse": "^2.4.5",
     "pdfkit": "^0.18.0",
     "reflect-metadata": "^0.2.2",
     "rxjs": "^7.8.1",