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/src/routes/auth.ts

@@ -16,6 +16,7 @@ import {
 } from "../services/discord.js";
 import { signToken } from "../services/jwt.js";
 import { logger } from "../services/logger.js";
+import { grantElysianRole } from "../services/webhook.js";
 import type { Player } from "@elysium/types";
 
 const authRouter = new Hono();
@@ -92,6 +93,12 @@ authRouter.get("/callback", async(context) => {
         },
       });
 
+      const inGuild = await grantElysianRole(player.discordId);
+      await prisma.player.update({
+        data:  { inGuild },
+        where: { discordId: player.discordId },
+      });
+
       const jwtToken = signToken(player.discordId);
       void logger.log("info", `New player registered: ${player.discordId}`);
       void logger.metric("user_registered", 1, { discordId: player.discordId });
@@ -104,10 +111,12 @@ authRouter.get("/callback", async(context) => {
       );
     }
 
+    const inGuild = await grantElysianRole(discordUser.id);
     const updated = await prisma.player.update({
       data: {
         avatar:        discordUser.avatar,
         discriminator: discordUser.discriminator,
+        inGuild:       inGuild,
         username:      discordUser.username,
       },
       where: { discordId: discordUser.id },

apps/api/src/routes/game.ts

@@ -760,6 +760,7 @@ gameRouter.get("/load", async(context) => {
         : computeHmac(JSON.stringify(freshState), secret);
       return context.json({
         currentSchemaVersion: currentSchemaVersion,
+        inGuild:              playerRecord.inGuild,
         loginBonus:           null,
         loginStreak:          playerRecord.loginStreak,
         offlineEssence:       0,
@@ -898,8 +899,10 @@ gameRouter.get("/load", async(context) => {
     const signature = secret === undefined
       ? undefined
       : computeHmac(JSON.stringify(state), secret);
+    const inGuild = playerRecord?.inGuild ?? false;
     return context.json({
       currentSchemaVersion,
+      inGuild,
       loginBonus,
       loginStreak,
       offlineEssence,