fix: refresh Discord avatar hash on every game load (#104)

Adds fetchDiscordUserById (bot token) to the Discord service and calls it
in parallel with the DB queries on game load. When the returned hash
differs from the stored value the Player record is updated and the hash
is immediately synced into the returned game state, so the resource bar
always shows the player's current Discord avatar.

Also adds onError fallback: if the avatar URL is stale before the next
load, the resource bar component now derives the URL fresh from state on
every render rather than caching it.

apps/api/test/services/discord.spec.ts

@@ -104,4 +104,53 @@ describe("discord service", () => {
       await expect(exchangeCode("some_code")).rejects.toBe("raw string error");
     });
   });
+
+  describe("fetchDiscordUserById", () => {
+    it("returns null when DISCORD_BOT_TOKEN is missing", async () => {
+      delete process.env["DISCORD_BOT_TOKEN"];
+      const { fetchDiscordUserById } = await import("../../src/services/discord.js");
+      const result = await fetchDiscordUserById("123456");
+      expect(result).toBeNull();
+    });
+
+    it("returns null when DISCORD_BOT_TOKEN is empty", async () => {
+      process.env["DISCORD_BOT_TOKEN"] = "";
+      const { fetchDiscordUserById } = await import("../../src/services/discord.js");
+      const result = await fetchDiscordUserById("123456");
+      expect(result).toBeNull();
+    });
+
+    it("returns null when response is not ok", async () => {
+      process.env["DISCORD_BOT_TOKEN"] = "bot_token";
+      mockFetch.mockResolvedValueOnce({ ok: false, statusText: "Not Found" });
+      const { fetchDiscordUserById } = await import("../../src/services/discord.js");
+      const result = await fetchDiscordUserById("123456");
+      expect(result).toBeNull();
+    });
+
+    it("returns null when fetch throws", async () => {
+      process.env["DISCORD_BOT_TOKEN"] = "bot_token";
+      mockFetch.mockRejectedValueOnce(new Error("network error"));
+      const { fetchDiscordUserById } = await import("../../src/services/discord.js");
+      const result = await fetchDiscordUserById("123456");
+      expect(result).toBeNull();
+    });
+
+    it("returns null when fetch throws a non-Error value", async () => {
+      process.env["DISCORD_BOT_TOKEN"] = "bot_token";
+      mockFetch.mockRejectedValueOnce("raw string error");
+      const { fetchDiscordUserById } = await import("../../src/services/discord.js");
+      const result = await fetchDiscordUserById("123456");
+      expect(result).toBeNull();
+    });
+
+    it("returns the user on success", async () => {
+      process.env["DISCORD_BOT_TOKEN"] = "bot_token";
+      const user = { id: "123456", username: "testuser", discriminator: "0", avatar: "abc123" };
+      mockFetch.mockResolvedValueOnce({ ok: true, json: () => Promise.resolve(user) });
+      const { fetchDiscordUserById } = await import("../../src/services/discord.js");
+      const result = await fetchDiscordUserById("123456");
+      expect(result).toMatchObject({ id: "123456", avatar: "abc123" });
+    });
+  });
 });