feat(admin): finish the screens that were stopping one step short

Five places where the data existed and the screen did not use it.

Booking a whole course had no button because it needs a doctor and the course
does not carry one — each session can be with a different doctor. The page now
asks for the doctor the same way the resource booking page does, and the button
explains that it is all-or-nothing before it is pressed.

A course whose package does not cover the remaining sessions is still valid —
the rest is simply charged normally — but nobody was told. The course response
carries package_balance and the shortfall, and the page warns. Before session
six, not during it.

The credit ledger already returned who recorded a row and which appointment it
belonged to, and showed neither. An adjustable ledger without the name of the
person who adjusted it is half an audit trail.

Version history printed a JSON blob of each version's effects, which does not
answer the question anyone actually has: what changed? It now diffs each
version against the previous one, field by field, and says so plainly when a
version changed nothing meaningful.

A resource with no calendar showed "—" for utilization. Null means undefined,
not zero, and the next step is always the same: set up the calendar. It is a
link now. The report range also accepts a custom from/to, kept in the URL like
the rest.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

assets/admin/pages/PolicySimulationPage.tsx

@@ -4,6 +4,7 @@ import { BeakerIcon } from '@heroicons/react/24/outline';
 import PageHeader from '../components/ui/PageHeader';
 import ConfirmDialog from '../components/ui/ConfirmDialog';
 import DataTable, { type Column } from '../components/ui/DataTable';
+import PolicyVersionDiff from '../components/PolicyVersionDiff';
 import { formatDate } from '../lib/utils';
 import { usePermissions } from '../hooks/usePermissions';
 import { usePolicies, usePolicy, usePolicySimulation } from '../hooks/usePolicies';
@@ -163,20 +164,7 @@ export default function PolicySimulationPage() {
       />
 
       {policy?.versions && policy.versions.length > 1 && (
-        <div className="card" style={{ marginBottom: 16 }}>
-          <h3 style={{ fontSize: 14, margin: '0 0 10px' }}>تاریخچهٔ نسخه‌ها</h3>
-          <div style={{ display: 'flex', flexDirection: 'column', gap: 6 }}>
-            {policy.versions.map((v) => (
-              <div key={v.version} style={{ display: 'flex', gap: 10, fontSize: 12 }}>
-                <span style={{ fontWeight: 600, minWidth: 60 }}>نسخهٔ {v.version}</span>
-                <span style={{ color: 'var(--text-3)' }}>{formatDate(v.created_at)}</span>
-                <span style={{ color: 'var(--text-2)' }}>
-                  {JSON.stringify((v.snapshot as { effects?: unknown }).effects)}
-                </span>
-              </div>
-            ))}
-          </div>
-        </div>
+        <PolicyVersionDiff versions={policy.versions as never} />
       )}
 
       <div style={{ overflowX: 'auto' }}>