docs(reference-app): collapse the walkthrough behind a disclosure (#196)

Shows the consent screen as a single hero image, then tucks the full four-step sequence behind a <details> so the reader can click through it without the section dominating the README. Uses the existing stills — no gif or video.

Author: ardetrick

README.md

@@ -244,26 +244,33 @@ jwk [like this](https://jwt.io/#debugger-io?token=eyJhbGciOiJSUzI1NiIsImtpZCI6Im
 
 ## See it work
 
-A walk through the authorization code flow with OpenID Connect, from login to real
-tokens. Run `./gradlew bootTestRun` and open http://localhost:8080 to click through it
-yourself.
+Log in, authorize the requested scopes, and the app exchanges the authorization code for
+real tokens from Hydra. Run `./gradlew bootTestRun` and open http://localhost:8080 to
+click through it yourself.
 
-Log in (the demo credentials are pre-filled):
+![consent screen](docs/images/authorization-code-flow/2-consent.png)
+
+<details>
+<summary>See the full flow, step by step</summary>
+
+Log in — the demo credentials are pre-filled.
 
 ![login screen](docs/images/authorization-code-flow/1-login.png)
 
-Authorize the scopes the application is requesting:
+Authorize the scopes the application is requesting.
 
 ![consent screen](docs/images/authorization-code-flow/2-consent.png)
 
-Hydra redirects back with an authorization code, which the app exchanges for tokens:
+Hydra redirects back with an authorization code, which the app exchanges for tokens.
 
 ![callback screen](docs/images/authorization-code-flow/3-callback-page.png)
 
-The result is a real access token, ID token, and refresh token from Hydra:
+The result is a real access token, ID token, and refresh token from Hydra.
 
 ![token response](docs/images/authorization-code-flow/4-tokens.png)
 
+</details>
+
 ## Building against a different testcontainers-ory-hydra version
 
 The `testcontainersOryHydraVersion` Gradle property overrides the version pinned in