[feat] add initial database schema with tables, triggers, and views

database/main/species_trait.sql

@@ -0,0 +1,21 @@
+create table species_trait
+(
+    species_id  INTEGER not null
+        references species
+            on delete cascade,
+    trait_id    INTEGER not null
+        references trait
+            on delete restrict,
+    source      TEXT    not null,
+    level       INTEGER,
+    param_value TEXT,
+    primary key (species_id, trait_id, source),
+    check (source IN ('AUTOMATISCH', 'TYPISCH', 'EMPFOHLEN'))
+);
+
+create index idx_species_trait_trait
+    on species_trait (trait_id);
+
+create index idx_species_trait_trait2
+    on species_trait (trait_id);
+