consolidate common action setup + migrate to ruff and pyrefly

.github/actions/setup-uv-python/action.yml

@@ -0,0 +1,30 @@
+name: "Setup Python + uv + sync"
+description: "Checkout, install uv, and uv sync (with optional groups, default Python 3.10)"
+inputs:
+  python-version:
+    description: "Python version to use"
+    required: false
+    default: "3.10"
+  groups:
+    description: "Comma-separated uv groups to sync (e.g. 'dev,docs'). Leave blank for default deps only."
+    required: false
+    default: ""
+
+runs:
+  using: "composite"
+  steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+
+    - name: Setup UV
+      uses: astral-sh/setup-uv@v6
+
+    - name: Sync environment
+      shell: bash
+      run: |
+        GROUP_FLAGS=()
+        if [ -n "${{ inputs.groups }}" ]; then
+          IFS=',' read -ra G <<< "${{ inputs.groups }}"
+          for g in "${G[@]}"; do GROUP_FLAGS+=( "--group" "$(echo $g | xargs)" ); done
+        fi
+        uv sync "${GROUP_FLAGS[@]}" --python "${{ inputs.python-version }}"