Add READMEs for remaining packages

- db-schema: Database schema types from kysely-codegen
- db: Database client and helper functions
- testing: Overview of testing packages
- test-helpers: Database testing utilities
- virtual-authenticator: WebAuthn virtual authenticator

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

packages/testing/virtual-authenticator/README.md

@@ -0,0 +1,39 @@
+# @reviq/virtual-authenticator
+
+WebAuthn virtual authenticator for testing passkey registration and authentication flows.
+
+## Usage
+
+```typescript
+import { VirtualAuthenticator } from "@reviq/virtual-authenticator";
+
+const authenticator = new VirtualAuthenticator({
+  aaguid: "00000000-0000-0000-0000-000000000000",
+});
+
+// Create a credential during registration
+const credential = await authenticator.create(
+  publicKeyCredentialCreationOptions,
+);
+
+// Use the credential during authentication
+const assertion = await authenticator.get(
+  publicKeyCredentialRequestOptions,
+);
+```
+
+## Exports
+
+### Classes
+- `VirtualAuthenticator` - Simulates a WebAuthn authenticator
+
+### Utilities
+- `base64urlToUint8Array(str)` - Decode base64url to bytes
+- `uint8ArrayToBase64url(bytes)` - Encode bytes to base64url
+- `parseAaguid(str)` - Parse an AAGUID string to bytes
+
+### Constants
+- `DEFAULT_AAGUID` - Default AAGUID for the virtual authenticator
+
+### Types
+- `VirtualAuthenticatorOptions` - Configuration options for the authenticator