Remove misleading "per month" from referral messaging

Referral bonuses are one-time credits, not monthly recurring. Updated:
- Referral landing page
- Profile referrals section
- Banner component
- Grant credits description
- Billing knowledge docs

Author: brandonkachen

packages/billing/knowledge.md

@@ -7,7 +7,7 @@ This package contains Codebuff's billing and credit management system.
 The billing system handles:
 
 - Credit balance calculation and tracking
-- Monthly credit grants and resets
+- Credit grants and resets
 - Auto top-up functionality
 - Credit grant operations (referrals, purchases, etc.)
 

packages/billing/src/grant-credits.ts

@@ -487,7 +487,7 @@ export async function triggerMonthlyResetAndGrant(params: {
           ...params,
           amount: referralBonus,
           type: 'referral',
-          description: 'Monthly referral bonus',
+          description: 'Referral bonus',
           expiresAt: newResetDate, // Referral credits expire at next reset
           operationId: referralOperationId,
           tx,

web/src/app/profile/components/referrals-section.tsx

@@ -124,7 +124,7 @@ export function ReferralsSection() {
           </CardTitle>
           <CardDescription className="text-green-700 dark:text-green-300">
             Refer a friend and <b>you'll both</b> earn {CREDITS_REFERRAL_BONUS}{' '}
-            credits per month!{' '}
+            bonus credits!{' '}
           </CardDescription>
         </CardHeader>
         <CardContent>

web/src/app/referrals/[code]/page.tsx

@@ -121,7 +121,7 @@ export default async function ReferralPage({
     >
       <CardWithBeams
         title={`${referrerDisplayName} invited you to Codebuff!`}
-        description={`Sign up and you'll both earn ${CREDITS_REFERRAL_BONUS} bonus credits per month.`}
+        description={`Sign up and you'll both earn ${CREDITS_REFERRAL_BONUS} bonus credits.`}
         content={
           <div className="text-center text-muted-foreground">
             Follow the steps below to get started, then redeem your referral

web/src/components/ui/banner.tsx

@@ -45,12 +45,12 @@ function BannerContent() {
             {isPersonalReferral ? (
               <>
                 {capitalize(referrer)} got you an extra {CREDITS_REFERRAL_BONUS}{' '}
-                credits per month!
+                bonus credits!
               </>
             ) : (
               <>
-                Refer a friend, and earn {CREDITS_REFERRAL_BONUS} credits per
-                month for both of you!
+                Refer a friend, and earn {CREDITS_REFERRAL_BONUS} bonus credits
+                for both of you!
               </>
             )}{' '}
             <Link