replace erd with png

Author: ScriptRaccoon

DATABASE.md

@@ -44,148 +44,4 @@ The database is built up incrementally and updated with the help of migration fi
 
 ## Diagram
 
-```mermaid
-erDiagram
-    categories {
-        text id PK
-        text name
-        text notation
-        text objects
-        text morphisms
-        text description
-        text nlab_link
-        text created_at
-    }
-
-    category_comments {
-        integer id PK
-        text category_id FK
-        text comment
-        text created_at
-    }
-
-    category_epimorphisms {
-        text category_id FK
-        text description
-        text reason
-        text created_at
-    }
-
-    category_isomorphisms {
-        text category_id FK
-        text description
-        text reason
-        text created_at
-    }
-
-    category_monomorphisms {
-        text category_id FK
-        text description
-        text reason
-        text created_at
-    }
-
-    category_non_properties {
-        text category_id FK
-        text non_property_id FK
-        text reason
-        integer is_deduced
-        integer position
-        text created_at
-    }
-
-    category_properties {
-        text category_id FK
-        text property_id FK
-        text reason
-        integer is_deduced
-        integer position
-        text created_at
-    }
-
-    category_tags {
-        text category_id FK
-        text tag FK
-        text created_at
-    }
-
-    implications {
-        text id PK
-        text reason
-        integer is_equivalence
-        integer is_deduced
-        text created_at
-    }
-
-    implication_assumptions {
-        text implication_id FK
-        text property_id FK
-        text created_at
-    }
-
-    implication_conclusions {
-        text implication_id FK
-        text property_id FK
-        text created_at
-    }
-
-    migrations {
-        text file PK
-        text applied_at
-    }
-
-    prefixes {
-        text prefix PK
-        text negation
-        text created_at
-    }
-
-    properties {
-        text id PK
-        text prefix FK
-        text description
-        text nlab_link
-        integer invariant_under_equivalences
-        text dual_property_id FK
-        text created_at
-    }
-
-    related_categories {
-        text category_id FK
-        text related_category_id FK
-        text created_at
-    }
-
-    related_properties {
-        text property_id FK
-        text related_property_id FK
-        text created_at
-    }
-
-    tags {
-        text tag PK
-        text description
-        text created_at
-    }
-
-    categories ||--o{ category_comments : has
-    categories ||--o{ category_epimorphisms : has
-    categories ||--o{ category_isomorphisms : has
-    categories ||--o{ category_monomorphisms : has
-    categories ||--o{ category_non_properties : has
-    categories ||--o{ category_properties : has
-    categories ||--o{ category_tags : has
-    categories ||--o{ related_categories : related_to
-
-    properties ||--o{ category_non_properties : referenced_by
-    properties ||--o{ category_properties : referenced_by
-    properties ||--o{ implication_assumptions : used_in
-    properties ||--o{ implication_conclusions : used_in
-    properties ||--o{ related_properties : related_to
-    prefixes ||--o{ properties : has
-
-    implications ||--o{ implication_assumptions : has
-    implications ||--o{ implication_conclusions : has
-
-    tags ||--o{ category_tags : tagged_by
-```
+![database diagram](/static/database-diagram.png)