feat(webapp): let users select the Free plan without GitHub verification

Selecting Free now provisions the plan immediately instead of routing
through a GitHub connect/verification step. Remove the 'Unlock Free plan' /
'Connect to GitHub' dialog, the GitHub-verified badge, and the account-
rejected state from the plan picker, simplify the setPlan free-result
handling to a success redirect, and delete the now-unreachable free-connect
return routes. The billing service provisions the free plan directly.

Author: matt-aitken

.server-changes/remove-github-verification-free-plan.md

@@ -0,0 +1,6 @@
+---
+area: webapp
+type: improvement
+---
+
+Selecting the Free plan no longer requires connecting and verifying a GitHub account. The plan is provisioned immediately when selected. The "Unlock Free plan"/"Connect to GitHub" dialog, the GitHub-verified badge, and the account-rejected state have been removed from the plan picker, along with the now-unreachable GitHub connect return routes.

apps/webapp/app/routes/_app.orgs.$organizationId.subscription.v3.free_connect_failed/route.tsx

@@ -73,7 +73,6 @@ export default function ChoosePlanPage() {
                 subscription={v3Subscription}
                 organizationSlug={organizationSlug}
                 hasPromotedPlan
-                showGithubVerificationBadge
                 periodEnd={periodEnd}
               />
             </div>