chore: monorepo scaffold, CI, MIT license

Bun workspaces (server/web/shared), typecheck+test gates, Gitea CI.
Refs PAI-90.

.gitea/workflows/ci.yml

@@ -0,0 +1,17 @@
+name: CI
+on:
+  push:
+    branches: [main]
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    container:
+      image: oven/bun:1
+    steps:
+      - name: Checkout
+        run: |
+          apt-get update -qq && apt-get install -y -qq git >/dev/null
+          git init -q . && git fetch -q --depth 1 "https://git.rehbock.xyz/${{ github.repository }}.git" "${{ github.sha }}" && git checkout -q FETCH_HEAD
+      - run: bun install --frozen-lockfile
+      - run: bun run typecheck
+      - run: bun test server