feat(precedent-library): add district and chair_name to edit form

Fields existed in DB and Precedent type but were missing from:
- PrecedentUpdateRequest (backend model)
- update_case_law allowed set (db layer)
- PrecedentPatch (frontend type)
- precedent-edit-sheet form state, inputs, and patch payload

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web-ui/src/lib/api/precedent-library.ts

@@ -414,6 +414,8 @@ export type PrecedentPatch = Partial<{
   source_type: SourceType;
   precedent_level: string;
   is_binding: boolean;
+  district: string;
+  chair_name: string;
 }>;
 
 export function useUpdatePrecedent() {