feat: grant Elysian role on auth and prompt non-members to join (#134)

## Summary

- Grants the Elysian Discord role to players on login/registration and persists an `inGuild` flag on the Player record
- Connects to the Discord Gateway via WebSocket to keep `inGuild` in sync as players join or leave the server
- Shows a dismissible "Join our community" modal to players who are not yet in the guild
- Hardens `inGuild` exposure through the load endpoint and game context
- Moves all non-secret Discord IDs (guild, role, client, redirect URI) out of env vars and into hardcoded constants; removes them from `prod.env`

## Test plan

- [ ] Lint, build, and test pipeline passes (100% coverage maintained)
- [ ] New player auth grants Elysian role and sets `inGuild: true`
- [ ] Existing player auth re-attempts role grant and updates `inGuild`
- [ ] Join community modal appears for players not in the guild
- [ ] Modal does not reappear within the same browser session after dismissal
- [ ] Gateway correctly sets `inGuild: true/false` on member add/remove events

✨ This issue was created with help from Hikari~ 🌸

Reviewed-on: #134
Co-authored-by: Hikari <hikari@nhcarrigan.com>
Co-committed-by: Hikari <hikari@nhcarrigan.com>

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

@@ -18,51 +18,31 @@ describe("discord service", () => {
   });
 
   describe("buildOAuthUrl", () => {
-    it("throws when DISCORD_CLIENT_ID is missing", async () => {
-      delete process.env["DISCORD_CLIENT_ID"];
-      process.env["DISCORD_REDIRECT_URI"] = "http://localhost/callback";
-      const { buildOAuthUrl } = await import("../../src/services/discord.js");
-      expect(() => buildOAuthUrl()).toThrow("Discord OAuth environment variables are required");
-    });
-
-    it("throws when DISCORD_REDIRECT_URI is missing", async () => {
-      process.env["DISCORD_CLIENT_ID"] = "client123";
-      delete process.env["DISCORD_REDIRECT_URI"];
-      const { buildOAuthUrl } = await import("../../src/services/discord.js");
-      expect(() => buildOAuthUrl()).toThrow("Discord OAuth environment variables are required");
-    });
-
     it("returns a URL with correct query params", async () => {
-      process.env["DISCORD_CLIENT_ID"] = "client123";
-      process.env["DISCORD_REDIRECT_URI"] = "http://localhost/callback";
       const { buildOAuthUrl } = await import("../../src/services/discord.js");
       const url = buildOAuthUrl();
-      expect(url).toContain("client_id=client123");
+      expect(url).toContain("client_id=1479551654264049908");
       expect(url).toContain("response_type=code");
       expect(url).toContain("scope=identify");
     });
   });
 
   describe("exchangeCode", () => {
-    it("throws when env vars are missing", async () => {
-      delete process.env["DISCORD_CLIENT_ID"];
+    it("throws when DISCORD_CLIENT_SECRET is missing", async () => {
+      delete process.env["DISCORD_CLIENT_SECRET"];
       const { exchangeCode } = await import("../../src/services/discord.js");
       await expect(exchangeCode("mycode")).rejects.toThrow("Discord OAuth environment variables are required");
     });
 
     it("throws when response is not ok", async () => {
-      process.env["DISCORD_CLIENT_ID"] = "cid";
       process.env["DISCORD_CLIENT_SECRET"] = "secret";
-      process.env["DISCORD_REDIRECT_URI"] = "http://localhost/cb";
       mockFetch.mockResolvedValueOnce({ ok: false, statusText: "Unauthorized" });
       const { exchangeCode } = await import("../../src/services/discord.js");
       await expect(exchangeCode("bad_code")).rejects.toThrow("Discord token exchange failed");
     });
 
     it("returns parsed body on success", async () => {
-      process.env["DISCORD_CLIENT_ID"] = "cid";
       process.env["DISCORD_CLIENT_SECRET"] = "secret";
-      process.env["DISCORD_REDIRECT_URI"] = "http://localhost/cb";
       const tokenData = { access_token: "tok", token_type: "Bearer", expires_in: 3600, refresh_token: "ref", scope: "identify" };
       mockFetch.mockResolvedValueOnce({ ok: true, json: () => Promise.resolve(tokenData) });
       const { exchangeCode } = await import("../../src/services/discord.js");
@@ -96,9 +76,7 @@ describe("discord service", () => {
 
   describe("exchangeCode non-Error throw", () => {
     it("re-throws when fetch rejects with a non-Error value", async () => {
-      process.env["DISCORD_CLIENT_ID"] = "cid";
       process.env["DISCORD_CLIENT_SECRET"] = "secret";
-      process.env["DISCORD_REDIRECT_URI"] = "http://localhost/cb";
       mockFetch.mockRejectedValueOnce("raw string error");
       const { exchangeCode } = await import("../../src/services/discord.js");
       await expect(exchangeCode("some_code")).rejects.toBe("raw string error");