fix: remove duplicate test_all_solutions.py and sync VIRTUAL_ENV_SETUP.md

- Delete .dev/tests/test_all_solutions.py (duplicate of tests_solutions/)
- Update VIRTUAL_ENV_SETUP.md to include MkDocs packages in requirements section
- Verify README.md and TESTING.md documentation accuracy

Author: lufftw

.dev/VIRTUAL_ENV_SETUP.md

@@ -243,6 +243,12 @@ pytest-cov>=4.1.0       # Coverage reporting
 
 # Optional packages (for complexity estimation):
 big-O>=0.10.0           # Time complexity estimation
+
+# Documentation generation (MkDocs):
+mkdocs>=1.6.0           # MkDocs static site generator
+mkdocs-material>=9.5.0  # Material theme for MkDocs
+mkdocs-minify-plugin>=0.7.0  # Minify HTML output
+mkdocs-include-markdown-plugin>=7.0.0  # Include markdown files
 ```
 
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