db: improve content hashing; cache only positive scan result

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: If8035bf1dcd598a992762b9c714253406a6a6964

src/commands/store.rs

@@ -38,6 +38,7 @@ impl StoreCommand for SqliteClipboardDb {
         Some(excluded_apps),
         min_size,
         max_size,
+        None, // no pre-computed hash for CLI store
       )?;
       log::info!("Entry stored");
     }