fix(docker): add .dockerignore to prevent secret leakage in image layers

Add .dockerignore to exclude .git/ and other unnecessary files from the
Docker build context. The ADD directive was copying the entire working
directory including .git/config, which contained personal access tokens
that were exposed in image layers and detected by trufflehog scans.

Also excludes CI/CD configs, test files, Python artifacts, virtual
environments, and build metadata to reduce image size.

Signed-off-by: Giulio Calacoci <giulio.calacoci@enterprisedb.com>

Author: gcalacoci

.dockerignore

@@ -0,0 +1,41 @@
+# Version control
+.git/
+.gitignore
+
+# CI/CD and development
+.github/
+.vscode/
+.idea/
+*.swp
+*.swo
+
+# Python artifacts
+__pycache__/
+*.pyc
+*.pyo
+*.egg-info/
+dist/
+build/
+.eggs/
+
+# Virtual environments
+.venv/
+venv/
+
+# Test and coverage
+tests/
+.pytest_cache/
+coverage.xml
+pytest.xml
+htmlcov/
+.coverage
+
+# Documentation and metadata (keep README.md — required by pyproject.toml)
+CHANGELOG.md
+CONTRIBUTING.md
+LICENSE
+personal/
+
+# Docker (prevent recursive builds)
+Dockerfile
+docker-compose*.yml