Add German translation support for Data Wizard plugin - #1

…entions, and QGIS API rules

Added `.coveragerc` for test coverage exclusions and created initial architecture guidelines, naming conventions, and API usage reference documents under `ai/core/`. Included test helpers (`conftest.py`, `layer_factories.py`), sample datasets, and pre-commit hooks for linting, security checks, and unit tests. Key focus: streamline development workflow for the Data Wizard plugin.

test_translations.py checks for the compiled i18n/Data_Wizard_de.qm, which
is deliberately gitignored as a build artifact. ci.yml runs the container
with "-v $(pwd):/plugins/data_wizard", which replaces the entire
/plugins/data_wizard tree from the image (including anything compiled
during the build) with the host checkout before CMD runs - so compiling
the translation only in a build step is silently discarded.

CMD now compiles i18n/*.ts -> *.qm itself before running pytest, so it
takes effect after the volume-mount override. The build-time compile step
is kept as a fallback for invocations without a volume mount (e.g. an
interactive shell).

Verified against the exact ci.yml invocation pattern (docker run --rm -v
<clean checkout>:/plugins/data_wizard ...) using a git-clean -fdX'd copy
of the working tree: 129 passed, 1 xfailed, test_qgis_translations green.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>