fix: leftover engine repair, just --no-sync, and ggml verify from #713 (#732)

* fix: leftover engine repair, just --no-sync, and ggml verify from #713

#713 only rewrote a broken config.json toward whisper_cpp, so a reinstall
that kept the old engine still died when vosk was the extra that installed.
verify_configured_engine now prefers SELECTED_ENGINE, then any working extra,
and the vosk fallback rewrites an existing file.

just recipes use uv run --no-sync so they do not prune extras from
just deps-all. CONTRIBUTING lists libgirepository-2.0-dev for Ubuntu 24.04.
An unverified ggml file is not loaded if unlink fails, and an unpinned name
is refused rather than deleted.

* fix(appimage): retry tooling downloads on curl reset

* fix(build): bootstrap .venv for --no-sync just recipes and cover the contributor path in CI

---------

Co-authored-by: Sergey Silaev <hello@8am.dev>

.github/workflows/unified-pipeline.yml

@@ -164,6 +164,48 @@ jobs:
           files: coverage.xml
           fail_ci_if_error: false
 
+  just-contributor-path:
+    name: 🧰 Contributor Path (just)
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    needs: [changes, python-lint]
+    if: needs.changes.outputs.python == 'true'
+    steps:
+      - uses: actions/checkout@v5
+
+      - name: Set up uv
+        uses: astral-sh/setup-uv@v6
+        with:
+          # Caches uv's download cache, not .venv/, so the checkout below stays
+          # the fresh clone this job exists to exercise.
+          enable-cache: true
+
+      - name: Install just
+        run: |
+          uv tool install rust-just
+          echo "$HOME/.local/bin" >> "$GITHUB_PATH"
+
+      - name: Install system dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y \
+            libgirepository-2.0-dev \
+            libcairo2-dev \
+            pkg-config \
+            python3-dev \
+            portaudio19-dev \
+            gir1.2-gtk-3.0 \
+            gir1.2-appindicator3-0.1 \
+            xdotool
+
+      # The rest of the pipeline drives uv directly, so nothing here checks that
+      # the workflow CONTRIBUTING documents still works. `just deps` is skipped on
+      # purpose: running it first would populate .venv/ and hide exactly the
+      # breakage this job is for, where `uv run --no-sync` finds no interpreter to
+      # run the tooling with.
+      - name: just test, from a clean checkout
+        run: just test
+
   appimage-smoke-test:
     name: 📦 Build AppImage (smoke test, ${{ matrix.arch }})
     runs-on: ${{ matrix.runner }}