Refactor API and enhance Angular integration

- Removed `ciTargetName` from `nx.json`.
- Updated `package.json` to include new dependencies: `@types/seedrandom`, `fast-check`, `happy-dom`, and `@nestjs/schedule`.
- Modified `pnpm-lock.yaml` to reflect the addition of new packages and their versions.
- Improved project documentation in `PROJECT_CONTEXT.md` to clarify the use of Zod schemas and Angular framework decisions.
- Introduced new Angular components and patterns in the `.agents/skills/frontend-angular` directory, including examples and reference materials for Angular 21+ features.

apps/api/src/app/missions/missions.controller.ts

@@ -0,0 +1,48 @@
+import {
+  Body,
+  Controller,
+  Get,
+  HttpCode,
+  HttpStatus,
+  NotFoundException,
+  Post,
+  UseGuards,
+} from '@nestjs/common';
+import {
+  MissionStateResponse,
+  MissionStateResponseSchema,
+  StartMissionRequestSchema,
+} from '@fog-explorer/api-interfaces';
+import { TwitchClaims, TwitchJwtGuard, TwitchJwtPayload } from '../auth/twitch-jwt.guard';
+import { MissionStoreService } from './mission-store.service';
+import { MissionsService } from './missions.service';
+
+@Controller('missions')
+@UseGuards(TwitchJwtGuard)
+export class MissionsController {
+  constructor(
+    private readonly store: MissionStoreService,
+    private readonly missions: MissionsService
+  ) {}
+
+  @Get('state')
+  async getState(
+    @TwitchClaims() claims: TwitchJwtPayload
+  ): Promise<MissionStateResponse> {
+    const state = await this.store.getStateForChannel(claims.channel_id);
+    return MissionStateResponseSchema.parse(state);
+  }
+
+  @Post('start')
+  @HttpCode(HttpStatus.CREATED)
+  async startMission(
+    @TwitchClaims() claims: TwitchJwtPayload,
+    @Body() body: unknown
+  ): Promise<MissionStateResponse> {
+    if (!claims.opaque_user_id.startsWith('U')) {
+      throw new NotFoundException('Anonymous viewers cannot start missions');
+    }
+    const { difficulty } = StartMissionRequestSchema.parse(body);
+    return this.missions.startMission(claims, difficulty);
+  }
+}