Move CI workflows to repo root .gitea/workflows/ (Gitea requires root location)

- 6 per-product CI workflows with path filters
- P1: Rust (cargo test + clippy + fmt)
- P2: Go agent (go test + vet) + Node SaaS (tsc + npm test)
- P3-P6: Node (npm ci + tsc + npm test)
- Removed old per-product .gitea dirs (Gitea ignores non-root workflows)

.gitea/workflows/ci-p1-route.yml

@@ -0,0 +1,37 @@
+name: CI — P1 Route (Rust)
+on:
+  push:
+    branches: [main]
+    paths: ['products/01-llm-cost-router/**']
+  pull_request:
+    paths: ['products/01-llm-cost-router/**']
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Cache cargo
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-cargo-${{ hashFiles('products/01-llm-cost-router/Cargo.lock') }}
+
+      - name: Run tests
+        run: cargo test --workspace
+        working-directory: products/01-llm-cost-router
+
+      - name: Clippy
+        run: cargo clippy --workspace -- -D warnings
+        working-directory: products/01-llm-cost-router
+
+      - name: Format check
+        run: cargo fmt --check
+        working-directory: products/01-llm-cost-router