The github-app-auth plugin's go.mod had a relative replace directive
(../molecule-monorepo/platform) that didn't resolve in Docker where
the plugin is at /plugin/ and the platform at /app/. This caused the
plugin's provisionhook.TokenProvider interface to come from a different
package path than the platform's, so the type assertion in
FirstTokenProvider() failed — "no token provider registered".
Fix: sed the plugin's go.mod replace to point at /app during Docker build.
Also added debug logging to GetInstallationToken for future diagnosis.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>