Feat[BE]: create project budget repo, entity, and migration

internal/database/migrations/20251127070744_create_project_budgets.up.sql

@@ -0,0 +1,31 @@
+CREATE TABLE project_budgets (
+    id BIGSERIAL PRIMARY KEY,
+    project_flock_id BIGINT NOT NULL,
+    nonstock_id BIGINT NOT NULL,
+    qty NUMERIC(15, 3) NOT NULL,
+    price NUMERIC(15, 3) NOT NULL,
+    created_at TIMESTAMPTZ DEFAULT now()
+);
+
+-- Tambahkan Foreign Key ke project_flocks
+DO $$
+BEGIN
+    IF EXISTS (SELECT 1 FROM pg_tables WHERE tablename = 'project_flocks') THEN
+        ALTER TABLE project_budgets
+            ADD CONSTRAINT fk_project_budgets_project_flock_id 
+            FOREIGN KEY (project_flock_id) REFERENCES project_flocks(id);
+    END IF;
+END $$;
+-- Tambahkan Foreign Key ke nonstocks
+DO $$
+BEGIN
+    IF EXISTS (SELECT 1 FROM pg_tables WHERE tablename = 'nonstocks') THEN
+        ALTER TABLE project_budgets
+            ADD CONSTRAINT fk_project_budgets_nonstock_id 
+            FOREIGN KEY (nonstock_id) REFERENCES nonstocks(id);
+    END IF;
+END $$;
+-- Index
+CREATE INDEX idx_project_budgets_project_flock_id ON project_budgets (project_flock_id);
+
+CREATE INDEX idx_project_budgets_nonstock_id ON project_budgets (nonstock_id);