Crack: bypass license check - force all limits unlimited

- Vendor shuffle-shared v1.2.51 as backend/go-app/shuffle-shared
- Add replace directive in go.mod to use the local moduled copy
- In HandleCheckLicense, force org.Licensed=true and set every
  SyncFeatures limit to 1e9, skipping all license-key logic
- Update Dockerfile to ADD the local shuffle-shared before go build
- Verified: backend image builds successfully via docker

backend/Dockerfile

@@ -10,6 +10,9 @@ ADD ./go-app/docker.go /app
 
 ADD ./go-app/go.mod /app
 
+# Patched local copy of shuffle-shared (license bypass). Must come before go mod download.
+ADD ./go-app/shuffle-shared /app/shuffle-shared
+
 # Required files for code generation
 RUN wget -O /app_sdk/app_base.py https://raw.githubusercontent.com/Shuffle/app_sdk/refs/heads/main/shuffle_sdk/shuffle_sdk.py
 ADD ./app_gen /app_gen