ci: use dev-docs container for docs CI

Run docs workflow inside ghcr.io/wphillipmoore/dev-docs:latest, removing
the custom Python setup action. uv and Python are pre-installed in the
container; uv sync --group docs still runs for mkdocstrings dependencies.

Relates-to: standard-tooling-docker#25

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: wphillipmoore

.github/workflows/docs.yml

@@ -18,18 +18,13 @@ jobs:
   deploy:
     name: "deploy: docs"
     runs-on: ubuntu-latest
+    container: ghcr.io/wphillipmoore/dev-docs:latest
     steps:
       - name: Checkout code
         uses: actions/checkout@v6
         with:
           fetch-depth: 0
 
-      - name: Set up Python
-        uses: wphillipmoore/standard-actions/actions/python/setup@develop
-        with:
-          python-version: "3.14"
-          cache-prefix: "uv-docs"
-
       - name: Install dependencies
         run: uv sync --frozen --group docs