feat: implement game filter to find games all selected people would play and add supporting test data

frontend/src/App.tsx

@@ -4,6 +4,7 @@ import { Login } from "./Login";
 import { PersonList } from "./PersonList";
 import { PersonDetails } from "./PersonDetails";
 import { GameList } from "./GameList";
+import { GameFilter } from "./GameFilter";
 import { BrowserRouter, Routes, Route, Link } from "react-router-dom";
 import "./App.css";
 import { apiFetch } from "./api";
@@ -52,6 +53,9 @@ function App() {
             <Link to="/games" className="nav-link">
               Games
             </Link>
+            <Link to="/filter" className="nav-link">
+              Filter
+            </Link>
           </div>
           <button onClick={handleLogout} className="btn-secondary">
             Logout
@@ -60,6 +64,7 @@ function App() {
         <Routes>
           <Route path="/" element={<PersonList people={people} />} />
           <Route path="/games" element={<GameList />} />
+          <Route path="/filter" element={<GameFilter />} />
           <Route path="/person/:name" element={<PersonDetails />} />
         </Routes>
       </div>

frontend/src/GameFilter.tsx

@@ -0,0 +1,142 @@
+import { useState, useEffect } from "react";
+import { Person, PersonList as PersonListProto } from "../items";
+import { apiFetch } from "./api";
+
+export function GameFilter() {
+  const [people, setPeople] = useState<Person[]>([]);
+  const [selectedPeople, setSelectedPeople] = useState<Set<string>>(new Set());
+  const [filteredGames, setFilteredGames] = useState<string[]>([]);
+
+  useEffect(() => {
+    apiFetch("/api")
+      .then((res) => res.arrayBuffer())
+      .then((buffer) => {
+        const list = PersonListProto.decode(new Uint8Array(buffer));
+        setPeople(list.person);
+      })
+      .catch((err) => console.error("Failed to fetch people:", err));
+  }, []);
+
+  useEffect(() => {
+    if (selectedPeople.size === 0) {
+      setFilteredGames([]);
+      return;
+    }
+
+    // Get all games where ALL selected people have "Would Play"
+    const selectedPersons = people.filter((p) => selectedPeople.has(p.name));
+
+    if (selectedPersons.length === 0) {
+      setFilteredGames([]);
+      return;
+    }
+
+    // Create a map of game -> set of people who would play it
+    const gameToPlayers = new Map<string, Set<string>>();
+
+    selectedPersons.forEach((person) => {
+      person.opinion.forEach((op) => {
+        if (op.wouldPlay) {
+          if (!gameToPlayers.has(op.title)) {
+            gameToPlayers.set(op.title, new Set());
+          }
+          gameToPlayers.get(op.title)!.add(person.name);
+        }
+      });
+    });
+
+    // Filter games where ALL selected people would play
+    const games = Array.from(gameToPlayers.entries())
+      .filter(([, players]) => players.size === selectedPeople.size)
+      .map(([game]) => game);
+
+    setFilteredGames(games);
+  }, [selectedPeople, people]);
+
+  const togglePerson = (name: string) => {
+    const newSelected = new Set(selectedPeople);
+    if (newSelected.has(name)) {
+      newSelected.delete(name);
+    } else {
+      newSelected.add(name);
+    }
+    setSelectedPeople(newSelected);
+  };
+
+  return (
+    <div>
+      <h2>Game Filter</h2>
+      <p style={{ color: "var(--text-muted)", marginBottom: "2rem" }}>
+        Select multiple people to find games that everyone would play
+      </p>
+
+      <div style={{ marginBottom: "3rem" }}>
+        <h3>Select People</h3>
+        <div className="grid-container">
+          {people.map((person) => (
+            <div
+              key={person.name}
+              className="list-item"
+              style={{
+                borderColor: selectedPeople.has(person.name)
+                  ? "var(--accent-color)"
+                  : "var(--border-color)",
+                cursor: "pointer",
+              }}
+              onClick={() => togglePerson(person.name)}
+            >
+              <div
+                style={{ display: "flex", alignItems: "center", gap: "0.5rem" }}
+              >
+                <input
+                  type="checkbox"
+                  checked={selectedPeople.has(person.name)}
+                  onChange={() => togglePerson(person.name)}
+                  style={{ cursor: "pointer" }}
+                />
+                <strong>{person.name}</strong>
+              </div>
+              <div
+                style={{
+                  fontSize: "0.9em",
+                  color: "var(--text-muted)",
+                  marginTop: "0.5rem",
+                }}
+              >
+                {person.opinion.length} opinion(s)
+              </div>
+            </div>
+          ))}
+        </div>
+      </div>
+
+      {selectedPeople.size > 0 && (
+        <div>
+          <h3>Games Everyone Would Play ({filteredGames.length})</h3>
+          {filteredGames.length > 0 ? (
+            <ul className="grid-container">
+              {filteredGames.map((game) => (
+                <li key={game} className="list-item">
+                  <strong>{game}</strong>
+                  <div
+                    style={{
+                      fontSize: "0.9em",
+                      color: "#4caf50",
+                      marginTop: "0.5rem",
+                    }}
+                  >
+                    ✓ All {selectedPeople.size} selected would play
+                  </div>
+                </li>
+              ))}
+            </ul>
+          ) : (
+            <p style={{ color: "var(--text-muted)", fontStyle: "italic" }}>
+              No games found where all selected people would play
+            </p>
+          )}
+        </div>
+      )}
+    </div>
+  );
+}

state.json

@@ -8,12 +8,53 @@
       "max_players": 90,
       "price": 0,
       "remote_id": 0
+    },
+    {
+      "title": "Test2",
+      "source": 1,
+      "multiplayer": true,
+      "min_players": 1,
+      "max_players": 1,
+      "price": 0,
+      "remote_id": 0
     }
   ],
   "users": [
     {
       "person": {
         "name": "John",
+        "opinion": [
+          {
+            "title": "Naramo Nuclear Plant V2",
+            "would_play": true
+          },
+          {
+            "title": "Test2",
+            "would_play": true
+          }
+        ]
+      },
+      "password_hash": "$2b$12$DRvTP/ibTWULkuJJr285bumRd7SG3n5bYkDpb09Qpklqf6FeTiHkC"
+    },
+    {
+      "person": {
+        "name": "John2",
+        "opinion": [
+          {
+            "title": "Naramo Nuclear Plant V2",
+            "would_play": false
+          },
+          {
+            "title": "Test2",
+            "would_play": true
+          }
+        ]
+      },
+      "password_hash": "$2b$12$DRvTP/ibTWULkuJJr285bumRd7SG3n5bYkDpb09Qpklqf6FeTiHkC"
+    },
+    {
+      "person": {
+        "name": "John3",
         "opinion": [
           {
             "title": "Naramo Nuclear Plant V2",