gh: listInstallations / listAppsInstalledRepo call the GitHub API twice on every cache miss

[whywaita]

Problem

Both cache wrappers in pkg/gh/installation.go fetch the data, store it in the cache, and then fetch it again for the return value:

inst, err := _listInstallations(ctx)
if err != nil { ... }

responseCache.Set(getCacheInstallationsKey(), inst, 1*time.Hour)

return _listInstallations(ctx)   // pkg/gh/installation.go:24 — second full API call (paginated!)

Same pattern in listAppsInstalledRepo (pkg/gh/installation.go:70). Every cache miss therefore costs 2× the API requests (each call paginates through all installations/repos at 100 per page), doubling rate-limit consumption for no benefit. Note the second call's error is also returned unwrapped, bypassing the wrapper's error message.

Suggested fix

return inst, nil

(and return repos, nil in listAppsInstalledRepo).