feat(p1): complete P1 foundation stage

- monorepo: pnpm workspace + go.work + pyproject.toml + commitlint/husky
- infra: docker-compose (minimal + full profiles) + init-sql + prometheus
- arch-scan: multi-language scanner skeleton (TS/Go/Python/Proto)
- shared-proto: buf v2 + classes.proto (ClassService CRUD contract)
- api-gateway: Go/Gin + JWT HS256 auth + reverse proxy + request ID
- classes: NestJS golden template (error system + observability + middleware + CRUD + tests)
- teacher-portal: Next.js + paper-feel UI design system
- CI/CD: 4 workflows (go/ts/py/proto)
- docs: migration guide + project_rules + coding-standards + git-workflow + ui-design-system + 004 + 9 module READMEs + known-issues + spec/plan migration + roadmap

.env.example

@@ -0,0 +1,32 @@
+# MySQL
+MYSQL_ROOT_PASSWORD=changeme
+MYSQL_DATABASE=next_edu_cloud
+MYSQL_USER=edu
+MYSQL_PASSWORD=changeme
+
+# Redis
+REDIS_PASSWORD=
+
+# JWT (P1 用 HS256 测试密钥，P2 改 RS256)
+JWT_SECRET=p1-dev-secret-change-in-production
+JWT_ISSUER=next-edu-cloud
+JWT_AUDIENCE=next-edu-cloud
+
+# 服务端口
+API_GATEWAY_PORT=8080
+CLASSES_SERVICE_PORT=3001
+TEACHER_PORTAL_PORT=3000
+
+# 数据库连接
+DATABASE_URL=mysql://edu:changeme@localhost:3306/next_edu_cloud
+REDIS_URL=redis://localhost:6379
+
+# 可观测性
+OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318
+LOG_LEVEL=info
+
+# Neo4j（P4 启用）
+NEO4J_PASSWORD=changeme
+
+# Kafka（P3 启用）
+KAFKA_BROKERS=localhost:9092