feat: Günther-Agent (Netzer-Style) + Expertenblick im TipModal

- AgentChat-Widget mit SSE-Streaming, Quick-Actions, Multiple-Choice
- /api/agent/chat + /api/agent/insight Routen
- Expertenblick-Panel im TipModal (lazy load)
- Günther-Icon

backend/package-lock.json

@@ -8,6 +8,7 @@
       "name": "wm2026-tippspiel-backend",
       "version": "1.0.0",
       "dependencies": {
+        "@anthropic-ai/sdk": "^0.82.0",
         "@staffbase/staffbase-plugin-sdk": "^1.3.7",
         "cors": "^2.8.5",
         "dotenv": "^16.4.5",
@@ -26,6 +27,35 @@
         "typescript": "^5.4.5"
       }
     },
+    "node_modules/@anthropic-ai/sdk": {
+      "version": "0.82.0",
+      "resolved": "https://registry.npmjs.org/@anthropic-ai/sdk/-/sdk-0.82.0.tgz",
+      "integrity": "sha512-xdHTjL1GlUlDugHq/I47qdOKp/ROPvuHl7ROJCgUQigbvPu7asf9KcAcU1EqdrP2LuVhEKaTs7Z+ShpZDRzHdQ==",
+      "license": "MIT",
+      "dependencies": {
+        "json-schema-to-ts": "^3.1.1"
+      },
+      "bin": {
+        "anthropic-ai-sdk": "bin/cli"
+      },
+      "peerDependencies": {
+        "zod": "^3.25.0 || ^4.0.0"
+      },
+      "peerDependenciesMeta": {
+        "zod": {
+          "optional": true
+        }
+      }
+    },
+    "node_modules/@babel/runtime": {
+      "version": "7.29.2",
+      "resolved": "https://registry.npmjs.org/@babel/runtime/-/runtime-7.29.2.tgz",
+      "integrity": "sha512-JiDShH45zKHWyGe4ZNVRrCjBz8Nh9TMmZG1kh4QTK8hCBTWBi8Da+i7s1fJw7/lYpM4ccepSNfqzZ/QvABBi5g==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=6.9.0"
+      }
+    },
     "node_modules/@colors/colors": {
       "version": "1.6.0",
       "resolved": "https://registry.npmjs.org/@colors/colors/-/colors-1.6.0.tgz",
@@ -1316,6 +1346,19 @@
         "url": "https://github.com/sponsors/sindresorhus"
       }
     },
+    "node_modules/json-schema-to-ts": {
+      "version": "3.1.1",
+      "resolved": "https://registry.npmjs.org/json-schema-to-ts/-/json-schema-to-ts-3.1.1.tgz",
+      "integrity": "sha512-+DWg8jCJG2TEnpy7kOm/7/AxaYoaRbjVB4LFZLySZlWn8exGs3A4OLJR966cVvU26N7X9TWxl+Jsw7dzAqKT6g==",
+      "license": "MIT",
+      "dependencies": {
+        "@babel/runtime": "^7.18.3",
+        "ts-algebra": "^2.0.0"
+      },
+      "engines": {
+        "node": ">=16"
+      }
+    },
     "node_modules/jsonwebtoken": {
       "version": "9.0.3",
       "resolved": "https://registry.npmjs.org/jsonwebtoken/-/jsonwebtoken-9.0.3.tgz",
@@ -2020,6 +2063,12 @@
         "node": ">= 14.0.0"
       }
     },
+    "node_modules/ts-algebra": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/ts-algebra/-/ts-algebra-2.0.0.tgz",
+      "integrity": "sha512-FPAhNPFMrkwz76P7cdjdmiShwMynZYN6SgOujD1urY4oNm80Ou9oMdmbR45LotcKOXoy7wSmHkRFE6Mxbrhefw==",
+      "license": "MIT"
+    },
     "node_modules/tsx": {
       "version": "4.21.0",
       "resolved": "https://registry.npmjs.org/tsx/-/tsx-4.21.0.tgz",