feat: initial elysium idle game prototype

Sets up the full monorepo with pnpm workspaces. Includes shared types
package, Hono API with Discord OAuth/JWT auth, Prisma v6 + MongoDB
Atlas, and React + Vite frontend with game loop, five tabs, and
Discord-linked save/load.

.gitea/workflows/ci.yml

@@ -0,0 +1,57 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  ci:
+    name: Lint, Build & Test
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Check dependency pins
+        uses: naomi-lgbt/dependency-pin-check@main
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: "22"
+
+      - name: Set up pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: "10"
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      - name: Lint (types package)
+        run: pnpm --filter @elysium/types lint
+
+      - name: Lint (API)
+        run: pnpm --filter @elysium/api lint
+
+      - name: Lint (web)
+        run: pnpm --filter @elysium/web lint
+
+      - name: Build (types package)
+        run: pnpm --filter @elysium/types build
+
+      - name: Build (API)
+        run: pnpm --filter @elysium/api build
+
+      - name: Build (web)
+        run: pnpm --filter @elysium/web build
+
+      - name: Test (API)
+        run: pnpm --filter @elysium/api test
+
+      - name: Test (web)
+        run: pnpm --filter @elysium/web test