feat(admin): add offering pricing and payment/refund UI

- admin-offerings-routes.js: PATCH /api/admin/offerings/:id (allowlisted fields), GET
  /api/admin/registrations/:id/payments, POST /api/admin/payments/:id/refund
- frontend: Pricing card on offering detail, Payments card (transaction history + record-refund
  action) on registration detail — admin/owner-gated, reusing existing admin UI conventions

frontend/src/admin/OfferingsView.jsx

@@ -188,6 +188,12 @@ function OfferingDetail({ offeringId, canAuthor, onBack }) {
             )}
           </div>
 
+          <div className={styles.card}>
+            <h3>Pricing</h3>
+            <p>{offering.price_amount === null ? <span className={styles.muted}>Free — no checkout required.</span> : <>{(offering.price_amount / 100).toFixed(2)} {offering.price_currency.toUpperCase()}</>}</p>
+            {canAuthor && <SetPriceForm offeringId={offeringId} current={offering} onSaved={reload} />}
+          </div>
+
           <div className={styles.card}>
             <h3>Launch readiness</h3>
             {!readiness ? <p className={styles.muted}>Loading…</p> : (
@@ -291,6 +297,36 @@ function CreateRegistrationForm({ offeringId, onCreated }) {
   )
 }
 
+function SetPriceForm({ offeringId, current, onSaved }) {
+  const [amount, setAmount] = useState(current.price_amount === null ? '' : (current.price_amount / 100).toFixed(2))
+  const [currency, setCurrency] = useState(current.price_currency || 'usd')
+  const [busy, setBusy] = useState(false)
+  const [error, setError] = useState(null)
+
+  const submit = async (e) => {
+    e.preventDefault()
+    setBusy(true); setError(null)
+    try {
+      await adminApi.updateOffering(offeringId, {
+        priceAmount: amount === '' ? null : Math.round(Number(amount) * 100),
+        priceCurrency: currency,
+      })
+      onSaved()
+    } catch (e) { setError(e.message) } finally { setBusy(false) }
+  }
+
+  return (
+    <form onSubmit={submit} style={{ marginTop: '0.5rem', display: 'flex', gap: '0.5rem', alignItems: 'end' }}>
+      {error && <div className={styles.errorBox}>{error}</div>}
+      <div><label className={styles.label}>Price (blank = free, no checkout)</label>
+        <input className={styles.input} type="number" min="0" step="0.01" value={amount} onChange={(e) => setAmount(e.target.value)} /></div>
+      <div><label className={styles.label}>Currency</label>
+        <input className={styles.input} value={currency} onChange={(e) => setCurrency(e.target.value.toLowerCase())} style={{ width: '5rem' }} /></div>
+      <button className={styles.btnSecondary} disabled={busy}>Save price</button>
+    </form>
+  )
+}
+
 function AddAgreementRequirementForm({ offeringId, allAgreements, onAdded }) {
   const [agreementId, setAgreementId] = useState('')
   const [busy, setBusy] = useState(false)
@@ -321,6 +357,7 @@ function RegistrationDetail({ registrationId, canAuthor, onBack }) {
   const [reg, setReg] = useState(null)
   const [agreementStatus, setAgreementStatus] = useState(null)
   const [notifs, setNotifs] = useState(null)
+  const [payments, setPayments] = useState(null)
   const [error, setError] = useState(null)
   const [notice, setNotice] = useState(null)
   const [busy, setBusy] = useState(false)
@@ -335,6 +372,7 @@ function RegistrationDetail({ registrationId, canAuthor, onBack }) {
     adminApi.registration(registrationId).then(setReg).catch((e) => setError(e.message))
     adminApi.registrationAgreementStatus(registrationId).then(setAgreementStatus).catch(() => {})
     adminApi.registrationNotifications(registrationId).then(setNotifs).catch(() => {})
+    adminApi.registrationPayments(registrationId).then(setPayments).catch(() => {})
   }, [registrationId])
   useEffect(reload, [reload])
 
@@ -387,6 +425,30 @@ function RegistrationDetail({ registrationId, canAuthor, onBack }) {
             )}
           </div>
 
+          <div className={styles.card}>
+            <h3>Payments</h3>
+            {!payments ? <p className={styles.muted}>Loading…</p> : payments.length === 0 ? <p className={styles.muted}>No checkout attempted — this offering may be free, or checkout hasn't started yet.</p> : (
+              <table>
+                <thead><tr><th>Amount</th><th>Status</th><th>Provider</th><th>Paid</th><th /></tr></thead>
+                <tbody>
+                  {payments.map((p) => (
+                    <tr key={p.transaction_id}>
+                      <td>{(p.amount / 100).toFixed(2)} {p.currency.toUpperCase()}</td>
+                      <td><span className={`${styles.pill} ${p.status === 'paid' ? styles.pillOk : p.status === 'failed' ? styles.pillErr : styles.pillMuted}`}>{p.status.replace('_', ' ')}</span></td>
+                      <td className={styles.muted}>{p.provider}</td>
+                      <td className={styles.muted}>{p.paid_at ? new Date(p.paid_at).toLocaleString() : '—'}</td>
+                      <td>
+                        {canAuthor && p.status === 'paid' && (
+                          <button className={styles.linkBtn} onClick={withBusy(() => adminApi.recordRefund(p.transaction_id, 'refunded'))}>Record refund</button>
+                        )}
+                      </td>
+                    </tr>
+                  ))}
+                </tbody>
+              </table>
+            )}
+          </div>
+
           <div className={styles.card}>
             <h3>Communications</h3>
             {!notifs ? <p className={styles.muted}>Loading…</p> : notifs.length === 0 ? <p className={styles.muted}>None sent yet.</p> : (

frontend/src/admin/api.js

@@ -144,6 +144,9 @@ export const adminApi = {
   offering: (id) => get(`/api/admin/offerings/${id}`),
   createOffering: (fields) => post('/api/admin/offerings', fields),
   transitionOffering: (id, status) => post(`/api/admin/offerings/${id}/transition`, { status }),
+  updateOffering: (id, fields) => patch(`/api/admin/offerings/${id}`, fields),
+  registrationPayments: (id) => get(`/api/admin/registrations/${id}/payments`),
+  recordRefund: (transactionId, status) => post(`/api/admin/payments/${transactionId}/refund`, { status }),
   offeringReadiness: (id) => get(`/api/admin/offerings/${id}/readiness`),
   assignOfferingInstructor: (id, instructor_id, role) => post(`/api/admin/offerings/${id}/instructors`, { instructor_id, role }),
   offeringAgreementRequirements: (id) => get(`/api/admin/offerings/${id}/agreement-requirements`),