chore(ci): migrate Python tooling to uv and standardize workflow execution (#7386)

# Description of Changes

This PR modernizes the project's Python tooling across GitHub Actions by
migrating CI workflows from pip-based dependency management to `uv` and
aligning Python execution with the engine project's managed environment.

### What was changed

- Replaced `actions/setup-python` and ad-hoc `pip install` steps with
`astral-sh/setup-uv` across CI workflows.
- Configured shared `uv` dependency caching using
`engine/pyproject.toml` and `engine/uv.lock`.
- Updated Python script execution to use `uv run --project engine
--locked` for a consistent runtime environment.
- Replaced package installation steps with `uv sync` for the required
dependency groups (e.g. `tools` and `cucumber`).
- Added Docker image build validation for both production and
development AI engine images.
- Updated workflow cache configuration and Docker build context where
required.
- Removed obsolete Python requirements files that are no longer needed
after the migration.
- Applied minor Python code modernizations, including import cleanup,
modern built-in generic type annotations (`list[...]`, `tuple[...]`,
`float | None`), and small style improvements.
- Removed unnecessary Python formatter/linter extensions from the
development container configuration.

### Why the change was made

- Standardize Python dependency management across the repository.
- Reduce duplicated dependency installation logic in CI.
- Improve workflow performance through shared dependency caching.
- Ensure all Python utilities execute against the same locked dependency
set managed by the engine project.
- Simplify long-term maintenance by eliminating legacy requirements
files and pip-specific workflow steps.


---

## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [ ] I have performed a self-review of my own code
- [ ] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### Translations (if applicable)

- [ ] I ran
[`scripts/counter_translation.py`](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/docs/counter_translation.md)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have run `task check` to verify linters, typechecks, and tests
pass
- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md#7-testing)
for more details.

---------

Signed-off-by: Carsten Drewes <c.drewes@stud.uni-hannover.de>
Co-authored-by: albanobattistella <34811668+albanobattistella@users.noreply.github.com>
Co-authored-by: kastenherri <116314318+kastenherri@users.noreply.github.com>
Co-authored-by: Anthony Stirling <77850077+Frooodle@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: James Brunton <jbrunton96@gmail.com>

.github/workflows/docker-compose-tests.yml

@@ -69,16 +69,17 @@ jobs:
           sudo curl -SL "https://github.com/docker/compose/releases/download/v2.39.4/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
           sudo chmod +x /usr/local/bin/docker-compose
 
-      - name: Set up Python
-        uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
+      - name: Install uv
+        uses: astral-sh/setup-uv@c771a70e6277c0a99b617c7a806ffedaca235ff9 # v9.0.0
         with:
-          python-version: "3.12"
-          cache: "pip" # caching pip dependencies
-          cache-dependency-path: ./testing/cucumber/requirements.txt
+          enable-cache: true
+          cache-dependency-glob: |
+            engine/pyproject.toml
+            engine/uv.lock
 
-      - name: Pip requirements
+      - name: Install Cucumber and coverage dependencies
         run: |
-          pip install --require-hashes --only-binary=:all: -r ./testing/cucumber/requirements.txt
+          uv sync --project engine --locked --group cucumber --group tools
 
       - name: Extract JaCoCo agent for cucumber coverage
         # Stages build/jacoco/jacocoagent.jar where the coverage override
@@ -121,16 +122,10 @@ jobs:
             echo "report=false" >> "$GITHUB_OUTPUT"
           fi
 
-      - name: Install defusedxml for coverage summary
-        # coverage-summary.py parses JaCoCo XML through defusedxml -
-        # see the script header for context.
-        if: always() && steps.cucumber-coverage.outputs.report == 'true'
-        run: python -m pip install --quiet defusedxml
-
       - name: Cucumber coverage step summary
         if: always() && steps.cucumber-coverage.outputs.report == 'true'
         run: |
-          python scripts/coverage-summary.py \
+          uv run --project engine --locked --group tools python scripts/coverage-summary.py \
             --title "Cucumber (docker) JaCoCo coverage" \
             --jacoco "cucumber=build/reports/jacoco/cucumber/jacocoTestReport.xml" \
             --github-step-summary