feat: add database storage backend (#1091)

Co-authored-by: Elias Schneider <login@eliasschneider.com>

backend/resources/migrations/sqlite/20251110000000_storage_table.up.sql

@@ -0,0 +1,14 @@
+PRAGMA foreign_keys=OFF;
+BEGIN;
+-- The "storage" table contains file data stored in the database
+CREATE TABLE storage
+(
+    path       TEXT NOT NULL PRIMARY KEY,
+    data       BLOB NOT NULL,
+    size       INTEGER NOT NULL,
+    mod_time   DATETIME NOT NULL,
+    created_at DATETIME NOT NULL
+);
+
+COMMIT;
+PRAGMA foreign_keys=ON;