feat: Add thumbnail management for albums and people, implement face embedding functionality

libertas_api/migrations/20251115210437_create_face_embeddings.sql

@@ -0,0 +1,7 @@
+CREATE TABLE face_embeddings (
+    id UUID PRIMARY KEY,
+    face_region_id UUID NOT NULL REFERENCES face_regions(id) ON DELETE CASCADE,
+    model_id SMALLINT NOT NULL, 
+    embedding BYTEA NOT NULL
+);
+CREATE UNIQUE INDEX idx_face_embeddings_region_id ON face_embeddings (face_region_id);