refactor(tabs): add constraint to ensure that only one tab can be active

src/lib/migrations/003_create_tabs_table.sql

@@ -4,5 +4,5 @@ CREATE TABLE IF NOT EXISTS tabs (
     contents TEXT NOT NULL,
     query_id INTEGER,
     tab_index INTEGER NOT NULL,
-    active BOOL NOT NULL DEFAULT FALSE
+    active BOOL DEFAULT FALSE UNIQUE
 );

src/lib/repositories/tabs.ts

@@ -36,7 +36,7 @@ VALUES ${Array.from({ length: rows.length }).fill('(?,?,?,?,?, ?)').join(',\n')}
 					r.contents,
 					r.query_id ?? null,
 					r.tab_index,
-					r.tab_index === activeIndex
+					r.tab_index === activeIndex || null
 				])
 				.flat()
 		);