ci: reduce runner load

.gitea/workflows/ci.yml

@@ -7,6 +7,11 @@ on:
       - main
       - "feat/**"
 
+env:
+  CARGO_BUILD_JOBS: "2"
+  CARGO_INCREMENTAL: "0"
+  RUST_TEST_THREADS: "2"
+
 jobs:
   rust:
     name: Rust Checks
@@ -41,18 +46,16 @@ jobs:
       - name: Check formatting
         run: cargo fmt --all --check
 
-      - name: Check workspace
-        run: cargo check --workspace
-
       - name: Run clippy
-        run: cargo clippy --workspace --all-targets --all-features -- -D warnings
+        run: cargo clippy --workspace --all-targets --all-features --jobs "$CARGO_BUILD_JOBS" -- -D warnings
 
       - name: Run tests
-        run: cargo test --workspace --all-targets
+        run: cargo test --workspace --all-targets --jobs "$CARGO_BUILD_JOBS"
 
   ui:
     name: UI Checks
     runs-on: ubuntu-latest
+    needs: rust
 
     steps:
       - name: Checkout
@@ -72,12 +75,10 @@ jobs:
         working-directory: apps/ui
         run: npm run build
 
-      - name: Build UI image
-        run: docker build -f apps/ui/Dockerfile .
-
   frontend-e2e:
     name: Frontend E2E
     runs-on: ubuntu-latest
+    needs: ui
     services:
       crank-e2e-postgres:
         image: postgres:16-alpine
@@ -119,7 +120,7 @@ jobs:
         run: npx playwright install --with-deps chromium
 
       - name: Prebuild e2e services
-        run: cargo build -p admin-api -p mcp-server
+        run: cargo build -p admin-api -p mcp-server --jobs "$CARGO_BUILD_JOBS"
 
       - name: Run Playwright e2e
         working-directory: apps/ui
@@ -133,6 +134,7 @@ jobs:
   deployment:
     name: Deployment Manifests
     runs-on: ubuntu-latest
+    needs: ui
 
     steps:
       - name: Checkout