Fix TypeScript compilation issues in packages

- Add explicit type annotations for isolatedDeclarations
- Export Database type alias from db-schema
- Fix import paths and add proper type exports
- Update common schemas with better exports

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packages/db-schema/src/index.ts

@@ -4,7 +4,6 @@
  * @module @reviq/db-schema
  */
 
-export * from "./types.js";
-
 // Re-export DB as Database for convenience
 export type { DB as Database } from "./types.js";
+export * from "./types.js";

packages/db-schema/src/types.ts

@@ -16,9 +16,9 @@ export type Json = JsonValue;
 
 export type JsonArray = JsonValue[];
 
-export type JsonObject = {
+export interface JsonObject {
   [x: string]: JsonValue | undefined;
-};
+}
 
 export type JsonPrimitive = boolean | number | string | null;