feat: add attachment upload to Edit Appointment form (disk, scanned, screenshot with crop)

Lets staff attach files to an appointment directly from the edit form via
local disk upload, picking a previously-saved scanned attachment, or an
inline screenshot with crop-before-save (matching the Copy Agent page's
crop UX), instead of detouring through the Copy Agent page. Also fixes a
latent data-loss bug in claim-form's save-for-appointment call, which
replaced all AppointmentFile rows instead of merging with existing ones.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/Backend/src/storage/appointment-procedures-storage.ts

@@ -46,6 +46,10 @@ export interface IAppointmentProceduresStorage {
   deleteProcedure(id: number): Promise<void>;
   clearByAppointmentId(appointmentId: number): Promise<void>;
   getAppointmentFiles(appointmentId: number): Promise<AppointmentFileMeta[]>;
+  addAppointmentFile(
+    appointmentId: number,
+    file: AppointmentFileMeta
+  ): Promise<AppointmentFileMeta & { id: number }>;
   getAppointmentIdsWithProcedures(ids: number[]): Promise<Set<number>>;
   getProcedureCodesByAppointmentIds(ids: number[]): Promise<Map<number, string[]>>;
 }
@@ -201,4 +205,24 @@ export const appointmentProceduresStorage: IAppointmentProceduresStorage = {
       filePath: f.filePath,
     }));
   },
+
+  async addAppointmentFile(
+    appointmentId: number,
+    file: AppointmentFileMeta
+  ): Promise<AppointmentFileMeta & { id: number }> {
+    const row = await db.appointmentFile.create({
+      data: {
+        appointmentId,
+        filename: file.filename,
+        mimeType: file.mimeType ?? null,
+        filePath: file.filePath ?? null,
+      },
+    });
+    return {
+      id: row.id,
+      filename: row.filename,
+      mimeType: row.mimeType,
+      filePath: row.filePath,
+    };
+  },
 };