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

packages/shared-proto/buf.gen.yaml

@@ -0,0 +1,8 @@
+version: v2
+plugins:
+  - remote: buf.build/protocolbuffers/go
+    out: ../shared-go/gen/proto
+  - remote: buf.build/protocolbuffers/js
+    out: ../shared-ts/gen/proto
+  - remote: buf.build/protocolbuffers/python
+    out: ../shared-py/gen/proto