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>

database/seeders/data/README.md

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+# Seeder Data
+
+Drop example documents here. The seeder reads these files and loads them into PostgreSQL, which then triggers embedding generation via the AI service.
+
+## Option 1: Drop raw Office/PDF files
+
+Put `.docx`, `.pptx`, `.xlsx`, `.pdf` files in the `raw/` folder, then run the converter:
+
+```bash
+cd ai-service
+pip install python-docx python-pptx openpyxl pymupdf chardet
+python convert.py                       # convert all files in raw/
+python convert.py --out kennis_artikelen # output to a specific subfolder
+python convert.py path/to/file.docx     # convert a single file
+```
+
+This extracts text, preserves structure (headings, tables, slides), and writes markdown files with frontmatter into the `documents/` folder (or whichever `--out` you specify).
+
+## Option 2: Write markdown directly
+
+Each file is **Markdown with YAML frontmatter**. The seeder parses the frontmatter for metadata and the body as content.
+
+## Folder Structure
+
+```
+data/
+  raw/                 ← DROP OFFICE/PDF FILES HERE (auto-converted)
+  themas/              ← Strategic themes
+  projects/            ← Project descriptions (linked to a thema)
+  documents/           ← Meeting notes, specs, analyses (linked to a project)
+  kennis_artikelen/    ← Knowledge articles (standalone)
+  besluiten/           ← Decisions with rationale (linked to a project)
+  lessons_learned/     ← Lessons learned (linked to a project + fase)
+```
+
+## File Templates
+
+### themas/waterkwaliteit.md
+```markdown
+---
+naam: Waterkwaliteit & Monitoring
+beschrijving: Innovaties rondom waterkwaliteitsbewaking en meetnetwerken
+prioriteit: hoog
+---
+```
+
+### projects/sensor-netwerk.md
+```markdown
+---
+naam: Sensor Netwerk Pilot
+thema: Waterkwaliteit & Monitoring
+eigenaar: Jan de Vries
+status: experiment
+prioriteit: hoog
+startdatum: 2025-09-01
+streef_einddatum: 2026-06-30
+---
+
+Beschrijving van het project hier. Kan meerdere alinea's zijn.
+Dit wordt het `beschrijving` veld.
+```
+
+### documents/notulen-stuurgroep-2026-03.md
+```markdown
+---
+titel: Notulen Stuurgroep 15 maart 2026
+project: Sensor Netwerk Pilot
+type: vergaderverslag
+auteur: Pieter Jansen
+versie: 1
+---
+
+De volledige documentinhoud hier. Kan lang zijn — wordt automatisch
+gechunkt als het meer dan 1500 tekens is.
+```
+
+### kennis_artikelen/iot-waterbeheer.md
+```markdown
+---
+titel: IoT-sensoren in het waterbeheer
+auteur: Lisa de Groot
+tags: [IoT, sensoren, waterbeheer, telemetrie]
+---
+
+Artikelinhoud hier. Alles na de frontmatter wordt `inhoud`.
+```
+
+### besluiten/go-pilot-sensor.md
+```markdown
+---
+titel: Go voor pilotfase Sensor Netwerk
+project: Sensor Netwerk Pilot
+type: go_no_go
+status: goedgekeurd
+datum: 2026-02-20
+---
+
+Beschrijving van het besluit.
+
+## Onderbouwing
+
+De onderbouwing / rationale hier.
+```
+
+### lessons_learned/sensor-kalibratie.md
+```markdown
+---
+titel: Kalibratiefrequentie pH-sensoren onderschat
+project: Sensor Netwerk Pilot
+fase: experiment
+tags: [sensoren, kalibratie, pH]
+---
+
+Wat we geleerd hebben. Body wordt `inhoud`.
+```
+
+## Naming Convention
+
+Use lowercase slugs: `korte-beschrijving.md`. The filename is not stored — all metadata comes from frontmatter.
+
+## Tips
+
+- Write in Dutch (the embedding model and full-text search are configured for Dutch)
+- Real content is better than lorem ipsum — the search quality depends on it
+- Longer documents are fine — they get chunked automatically
+- Link projects to themas and documents to projects via the `thema:` and `project:` fields (matched by naam)