Add document converter, seeder data structure, and project wiki

- ai-service/convert.py: converts Office/PDF files to markdown with frontmatter
- database/seeders/data/: folder structure for themas, projects, documents, etc.
- database/seeders/data/raw/: drop zone for Office/PDF files to convert
- wiki/: project architecture, concepts, and knowledge graph documentation
- Remove unused Laravel example tests

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ai-service/requirements.txt

@@ -9,3 +9,10 @@ numpy>=1.26.0
 pydantic>=2.0.0
 python-dotenv>=1.0.0
 httpx>=0.27.0
+
+# Document extraction
+python-docx>=1.1.0
+python-pptx>=0.6.23
+openpyxl>=3.1.0
+pymupdf>=1.24.0
+chardet>=5.2.0