fix(share): correct shared link URL to include /api prefix

The shared link URL was generated as {base_url}/s/{token} but the
API endpoint is actually at /api/s/{token}. This caused 404 errors
when users accessed shared links.

Fixes #101

src/application/dtos/share_dto.rs

@@ -45,7 +45,7 @@ pub struct UpdateShareDto {
 /// Extension methods to convert between DTOs and domain entities
 impl ShareDto {
     pub fn from_entity(share: &Share, base_url: &str) -> Self {
-        let url = format!("{}/s/{}", base_url, share.token());
+        let url = format!("{}/api/s/{}", base_url, share.token());
 
         Self {
             id: share.id().to_string(),