refactor(vercel): Enhance Vercel integration handling with ResultAsync and improve error management

- Updated VercelSettingsPresenter to utilize ResultAsync for better error handling and flow control.
- Refactored API key regeneration to sync directly with Vercel, improving reliability.
- Enhanced onboarding and connection routes to handle optional parameters and errors more gracefully.
- Improved JSON parsing with safe handling using Result from neverthrow.
- Updated referral source management to use Zod for type safety.
- General code cleanup and consistency improvements across Vercel-related services and routes.

Author: 0ski

apps/webapp/app/components/integrations/VercelOnboardingModal.tsx

@@ -33,7 +33,6 @@ import { BuildSettingsFields } from "~/components/integrations/VercelBuildSettin
 import { OctoKitty } from "~/components/GitHubLoginButton";
 import {
   ConnectGitHubRepoModal,
-  type GitHubAppInstallation,
 } from "~/routes/resources.orgs.$organizationSlug.projects.$projectParam.env.$envParam.github";
 import {
   type SyncEnvVarsMapping,
@@ -337,7 +336,7 @@ export function VercelOnboardingModal({
         setState("loading-env-vars");
       }
     }
-  }, [state, onboardingData, hasStagingEnvironment]);
+  }, [state, onboardingData, hasStagingEnvironment, fromMarketplaceContext]);
 
   const secretEnvVars = envVars.filter((v) => v.isSecret);
   const syncableEnvVars = envVars.filter((v) => !v.isSecret);
@@ -990,7 +989,7 @@ export function VercelOnboardingModal({
                   <div className="flex flex-col gap-3">
                     <div className="flex items-center gap-3">
                       <ConnectGitHubRepoModal
-                        gitHubAppInstallations={gitHubAppInstallations as GitHubAppInstallation[]}
+                        gitHubAppInstallations={gitHubAppInstallations}
                         organizationSlug={organizationSlug}
                         projectSlug={projectSlug}
                         environmentSlug={environmentSlug}

apps/webapp/app/models/orgIntegration.server.ts

@@ -109,7 +109,8 @@ export class OrgIntegrationRepository {
     // The user goes to Vercel's marketplace to install the integration
     // After installation, Vercel redirects to our callback with the authorization code
     const redirectUri = encodeURIComponent(`${env.APP_ORIGIN}/vercel/callback`);
-    return `https://vercel.com/integrations/${env.VERCEL_INTEGRATION_APP_SLUG}/new?state=${state}&redirect_uri=${redirectUri}`;
+    const encodedState = encodeURIComponent(state);
+    return `https://vercel.com/integrations/${env.VERCEL_INTEGRATION_APP_SLUG}/new?state=${encodedState}&redirect_uri=${redirectUri}`;
   }
 
   static slackAuthorizationUrl(