fix(ci): swap maturin develop for pip install -e (no venv on runners)

The previous CI change called `maturin develop --release --extras
dev,full`, but `maturin develop` requires an active virtualenv and the
GitHub-hosted Python from setup-python lives in the toolcache, not in
a venv. All 12 matrix jobs (3 OS x 4 Python) failed with:

    💥 maturin failed
    Caused by: Couldn't find a virtualenv or conda environment...

Use `pip install -e ".[dev,full]" --no-build-isolation` instead: pip
invokes maturin via PEP 660, builds the Rust extension and installs
treemapper + extras in one shot. `--no-build-isolation` reuses the
already-installed maturin and skips spinning up a fresh build venv.

Also drop the `bench-image` and `smoke-bench` jobs from CI — they
built a Docker image from `Dockerfile.bench`, which was deleted in the
previous commit as paper-track scaffolding. The bench-sweep workflow
is workflow_dispatch-only and orthogonal to the release path.

Author: nikolay-e

.github/workflows/ci.yml

@@ -155,19 +155,20 @@ jobs:
           key: cargo-${{ runner.os }}-py${{ matrix.python-version }}-${{ hashFiles('diffctx/Cargo.lock') }}
           restore-keys: cargo-${{ runner.os }}-py${{ matrix.python-version }}-
 
-      - name: Install Python dev tools
+      - name: Install build backend
         run: |
           python -m pip install --upgrade pip
           pip install "maturin>=1.10,<1.11"
 
-      - name: Build and install treemapper (with Rust _diffctx)
+      - name: Build and install treemapper (with Rust _diffctx) and dev deps
         shell: bash
         env:
           PYO3_USE_ABI3_FORWARD_COMPATIBILITY: "1"
         run: |
-          # maturin develop builds the Rust extension and installs the project editable.
-          # Use --extras for dev/tree-sitter so tests have all deps available.
-          maturin develop --release --extras dev,full
+          # PEP 660 editable install — maturin builds the Rust extension and
+          # pip installs everything (treemapper + [dev,full] extras). Skip build
+          # isolation since we just installed maturin in this env.
+          pip install -e ".[dev,full]" --no-build-isolation
 
       - name: Run Tests with Coverage
         shell: bash
@@ -260,78 +261,3 @@ jobs:
 
       - name: Check import contracts
         run: lint-imports
-
-  # ============================================================================
-  # Bench image — build and push to GHCR on every push to main
-  # ============================================================================
-  bench-image:
-    name: Build bench image
-    if: github.event_name == 'push' && github.ref == 'refs/heads/main'
-    runs-on: ubuntu-latest
-    permissions:
-      contents: read
-      packages: write
-
-    steps:
-      - name: Free disk space
-        run: |
-          sudo rm -rf /usr/share/dotnet /usr/local/lib/android /opt/ghc /opt/hostedtoolcache/CodeQL || true
-          sudo docker image prune -af || true
-          df -h /
-
-      - uses: actions/checkout@v6
-
-      - uses: docker/setup-buildx-action@v4
-        with:
-          driver-opts: |
-            image=moby/buildkit:latest
-            network=host
-
-      - uses: docker/login-action@v4
-        with:
-          registry: ghcr.io
-          username: ${{ github.actor }}
-          password: ${{ secrets.GITHUB_TOKEN }}
-
-      - id: meta
-        uses: docker/metadata-action@v6
-        with:
-          images: ghcr.io/${{ github.repository_owner }}/treemapper-bench
-          tags: |
-            type=ref,event=branch
-            type=sha,prefix={{branch}}-,format=short
-            type=raw,value=latest,enable=true
-
-      - name: Build and push (amd64)
-        uses: docker/build-push-action@v7
-        with:
-          context: .
-          file: Dockerfile.bench
-          platforms: linux/amd64
-          push: true
-          tags: ${{ steps.meta.outputs.tags }}
-          labels: ${{ steps.meta.outputs.labels }}
-          cache-from: type=registry,ref=ghcr.io/${{ github.repository_owner }}/treemapper-bench:buildcache
-          cache-to: >-
-            type=registry,ref=ghcr.io/${{ github.repository_owner }}/treemapper-bench:buildcache,
-            mode=max,image-manifest=true,oci-mediatypes=true
-
-  # ============================================================================
-  # Trigger smoke bench sweep after image is built and tests pass
-  # ============================================================================
-  smoke-bench:
-    name: Trigger smoke sweep
-    needs: [bench-image]
-    if: github.event_name == 'push' && github.ref == 'refs/heads/main'
-    runs-on: ubuntu-latest
-    permissions:
-      actions: write
-    steps:
-      - name: Dispatch bench-sweep (smoke)
-        run: |
-          gh workflow run bench-sweep.yml \
-            --repo "${{ github.repository }}" \
-            --ref main \
-            --field mode=smoke
-        env:
-          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}