Make ancestor cols not nullable, add fk constraints

Also removed the temporary backfill, now that it is complete.

Updates models so cols are not optional.

src/plugin_processor.rs

@@ -62,7 +62,7 @@ pub async fn process_plugin(
                     name: &db_file.name,
                     hash: hash as i64,
                     file_id: db_file.id,
-                    mod_id: Some(db_mod.id),
+                    mod_id: db_mod.id,
                     version: plugin.header.version as f64,
                     size: plugin_buf.len() as i64,
                     author,
@@ -134,8 +134,8 @@ pub async fn process_plugin(
                 .map(|(db_cell, plugin_cell)| UnsavedPluginCell {
                     plugin_id: plugin_row.id,
                     cell_id: db_cell.id,
-                    file_id: Some(db_file.id),
-                    mod_id: Some(db_mod.id),
+                    file_id: db_file.id,
+                    mod_id: db_mod.id,
                     editor_id: plugin_cell.editor_id.as_ref().map(|id| id.as_ref()),
                 })
                 .collect();