Add source manager and inline citing with 'sourced' badges

New /trees/[id]/sources page (list + create sources). Person-detail page now loads tree sources + citations and shows a '✓ N sourced' badge with an inline cite picker (source + page) on each event and on the person. Tree view links to Sources. Regenerated the OpenAPI client.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Justin Paul <justin@jpaul.me>

frontend/app/trees/[id]/page.tsx

@@ -56,9 +56,14 @@ export default function TreeDetailPage() {
 
   return (
     <div className="space-y-6">
-      <Link href="/trees" className="text-sm text-[var(--muted)] hover:underline">
-        ← All trees
-      </Link>
+      <div className="flex items-center justify-between">
+        <Link href="/trees" className="text-sm text-[var(--muted)] hover:underline">
+          ← All trees
+        </Link>
+        <Link href={`/trees/${treeId}/sources`} className="text-sm text-bronze hover:underline">
+          Sources →
+        </Link>
+      </div>
 
       <Card>
         <CardHeader>