feat: Update project structure and configuration files

backend/database/migrations/20250322100215_create_posts.sql

@@ -0,0 +1,25 @@
+-- +goose Up
+-- +goose StatementBegin
+CREATE TABLE posts(
+    id SERIAL8 PRIMARY KEY,
+    created_at timestamp NOT NULL DEFAULT now(),
+    updated_at timestamp NOT NULL DEFAULT now(),
+    deleted_at timestamp,
+    status int2 NOT NULL DEFAULT 0,
+    title varchar(128) NOT NULL,
+    description varchar(256) NOT NULL,
+    content text NOT NULL,
+    price int8 NOT NULL DEFAULT 0,
+    discount int2 NOT NULL DEFAULT 100,
+    views int8 NOT NULL DEFAULT 0,
+    likes int8 NOT NULL DEFAULT 0,
+    tags jsonb DEFAULT '{}' ::jsonb,
+    assets jsonb DEFAULT '{}' ::jsonb
+);
+
+-- +goose StatementEnd
+-- +goose Down
+-- +goose StatementBegin
+DROP TABLE posts;
+
+-- +goose StatementEnd