docs: replace MinIO with filesystem storage throughout

Remove all MinIO/S3 references from documentation and deployment
configs. Silo now uses local filesystem storage exclusively.

Updated files:
- docs/CONFIGURATION.md: storage section now documents filesystem backend
- docs/DEPLOYMENT.md: architecture diagram, external services, troubleshooting
- docs/INSTALL.md: remove MinIO setup, update architecture diagrams
- docs/SPECIFICATION.md: architecture, technology stack, file storage strategy
- docs/STATUS.md: storage backend status
- docs/GAP_ANALYSIS.md: file handling references
- docs/ROADMAP.md: file storage appendix entries
- deployments/config.prod.yaml: filesystem backend config
- deployments/systemd/silod.env.example: remove MinIO credential vars

docs/STATUS.md

@@ -15,7 +15,7 @@
 | Part number generator | Complete | Scoped sequences, category-based format |
 | API server (`silod`) | Complete | 78 REST endpoints via chi/v5 |
 | CLI tool (`silo`) | Complete | Item registration and management |
-| MinIO file storage | Complete | Upload, download, versioning, checksums |
+| Filesystem file storage | Complete | Upload, download, checksums |
 | Revision control | Complete | Append-only history, rollback, comparison, status/labels |
 | Project management | Complete | CRUD, many-to-many item tagging |
 | CSV import/export | Complete | Dry-run validation, template generation |
@@ -29,7 +29,7 @@
 | CSRF protection | Complete | nosurf on web forms |
 | Fuzzy search | Complete | sahilm/fuzzy library |
 | Web UI | Complete | React SPA (Vite + TypeScript), 6 pages, Catppuccin Mocha theme |
-| File attachments | Complete | Presigned uploads, item file association, thumbnails |
+| File attachments | Complete | Direct uploads, item file association, thumbnails |
 | Odoo ERP integration | Partial | Config and sync-log CRUD functional; push/pull are stubs |
 | Docker Compose | Complete | Dev and production configurations |
 | Deployment scripts | Complete | setup-host, deploy, init-db, setup-ipa-nginx |
@@ -56,7 +56,7 @@ FreeCAD workbench and LibreOffice Calc extension are maintained in separate repo
 | Service | Host | Status |
 |---------|------|--------|
 | PostgreSQL | psql.example.internal:5432 | Running |
-| MinIO | localhost:9000 (API) / :9001 (console) | Configured |
+| File Storage | /opt/silo/data (filesystem) | Configured |
 | Silo API | localhost:8080 | Builds successfully |
 
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