feat: recurring expenses and reports

internal/db/migrations/00012_create_budgets_table.sql

@@ -0,0 +1,24 @@
+-- +goose Up
+CREATE TABLE budgets (
+    id TEXT PRIMARY KEY NOT NULL,
+    space_id TEXT NOT NULL,
+    tag_id TEXT NOT NULL,
+    amount_cents INTEGER NOT NULL,
+    period TEXT NOT NULL CHECK (period IN ('weekly', 'monthly', 'yearly')),
+    start_date DATE NOT NULL,
+    end_date DATE,
+    is_active BOOLEAN NOT NULL DEFAULT TRUE,
+    created_by TEXT NOT NULL,
+    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    UNIQUE(space_id, tag_id, period),
+    FOREIGN KEY (space_id) REFERENCES spaces(id) ON DELETE CASCADE,
+    FOREIGN KEY (tag_id) REFERENCES tags(id) ON DELETE CASCADE,
+    FOREIGN KEY (created_by) REFERENCES users(id) ON DELETE CASCADE
+);
+
+CREATE INDEX idx_budgets_space_id ON budgets(space_id);
+
+-- +goose Down
+DROP INDEX IF EXISTS idx_budgets_space_id;
+DROP TABLE IF EXISTS budgets;