Stage 5: Add Prisma integration and enhance mission management

- Introduced Prisma as a dependency in package.json and updated pnpm-lock.yaml.
- Created Prisma module and service for database interactions.
- Added initial Prisma schema and migration for user, survivor, mission, and related entities.
- Implemented throttling in the API using @nestjs/throttler for rate limiting.
- Enhanced mission management logic to utilize Prisma for database transactions.
- Updated missions controller and service to handle mission state and participant management.
- Added Twitch PubSub service for real-time updates on mission states.

apps/api/src/app/tick-engine/twitch-pubsub.service.ts

@@ -0,0 +1,72 @@
+import { Injectable, Logger } from '@nestjs/common';
+import { createHmac } from 'crypto';
+import type { MissionStateResponse } from '@fog-explorer/api-interfaces';
+
+const PUBSUB_URL = 'https://api.twitch.tv/extensions/message';
+const TOKEN_TTL_SECONDS = 60;
+
+@Injectable()
+export class TwitchPubSubService {
+  private readonly logger = new Logger(TwitchPubSubService.name);
+
+  async broadcast(
+    channelId: string | null,
+    state: NonNullable<MissionStateResponse>
+  ): Promise<void> {
+    if (!channelId) return;
+
+    const clientId = process.env['TWITCH_CLIENT_ID'];
+    const secret = process.env['TWITCH_EXTENSION_SECRET'];
+    if (!clientId || !secret) return;
+
+    const token = buildServerToken(clientId, secret);
+    const payload = JSON.stringify({
+      content_type: 'application/json',
+      message: JSON.stringify(state),
+      targets: ['broadcast'],
+    });
+
+    if (Buffer.byteLength(payload, 'utf8') > 5000) {
+      this.logger.warn({ message: 'pubsub payload too large, skipping', channelId });
+      return;
+    }
+
+    try {
+      const res = await fetch(`${PUBSUB_URL}/${channelId}`, {
+        method: 'POST',
+        headers: {
+          'Authorization': `Bearer ${token}`,
+          'Client-Id': clientId,
+          'Content-Type': 'application/json',
+        },
+        body: payload,
+      });
+
+      if (!res.ok) {
+        this.logger.warn({
+          message: 'pubsub broadcast failed',
+          channelId,
+          status: res.status,
+        });
+      }
+    } catch (err) {
+      this.logger.error({ message: 'pubsub broadcast error', channelId, err });
+    }
+  }
+}
+
+function buildServerToken(clientId: string, secretB64: string): string {
+  const secretBytes = Buffer.from(secretB64, 'base64');
+  const exp = Math.floor(Date.now() / 1000) + TOKEN_TTL_SECONDS;
+
+  const header = Buffer.from(JSON.stringify({ alg: 'HS256', typ: 'JWT' })).toString('base64url');
+  const payload = Buffer.from(
+    JSON.stringify({ exp, user_id: clientId, role: 'external' })
+  ).toString('base64url');
+
+  const sig = createHmac('sha256', secretBytes)
+    .update(`${header}.${payload}`)
+    .digest('base64url');
+
+  return `${header}.${payload}.${sig}`;
+}