feat: add barter calculator page

app.py

@@ -945,5 +945,76 @@ def meds():
                            situations=situations)
 
 
+@app.route("/barters")
+def barters():
+    import requests as _req
+
+    API_URL = "https://api.tarkov.dev/graphql"
+    query = """
+    {
+      barters(lang: en) {
+        id
+        trader { name }
+        level
+        taskUnlock { name }
+        requiredItems {
+          item { id name shortName iconLink wikiLink }
+          count
+        }
+        rewardItems {
+          item { id name shortName iconLink wikiLink }
+          count
+        }
+      }
+    }
+    """
+    try:
+        resp = _req.post(API_URL, json={"query": query}, timeout=15)
+        data = resp.json()
+        raw_barters = data.get("data", {}).get("barters", [])
+    except Exception:
+        raw_barters = []
+
+    barter_list = []
+    for b in raw_barters:
+        reward_items = b.get("rewardItems", [])
+        required_items = b.get("requiredItems", [])
+        if not reward_items or not required_items:
+            continue
+
+        # Use first reward item as the "output" item
+        reward = reward_items[0]
+        reward_item = reward.get("item") or {}
+        reward_count = reward.get("count", 1)
+
+        required = []
+        for ri in required_items:
+            item = ri.get("item") or {}
+            required.append({
+                "id": item.get("id", ""),
+                "name": item.get("name", "Unknown"),
+                "short": item.get("shortName", ""),
+                "icon": item.get("iconLink"),
+                "count": ri.get("count", 1),
+            })
+
+        task_unlock = b.get("taskUnlock")
+        barter_list.append({
+            "id": b.get("id", ""),
+            "trader": (b.get("trader") or {}).get("name", "Unknown"),
+            "level": b.get("level", 1),
+            "task_unlock": task_unlock.get("name") if task_unlock else None,
+            "reward_name": reward_item.get("name", "Unknown"),
+            "reward_short": reward_item.get("shortName", ""),
+            "reward_icon": reward_item.get("iconLink"),
+            "reward_wiki": reward_item.get("wikiLink"),
+            "reward_count": reward_count,
+            "required": required,
+        })
+
+    barter_list.sort(key=lambda b: (b["trader"], b["level"], b["reward_name"]))
+    return render_template("barters.html", barters=barter_list)
+
+
 if __name__ == "__main__":
     app.run(host="0.0.0.0", port=5000, debug=True)