Add portable mode with removable media detection and scanning

src/core/database.rs

@@ -1786,6 +1786,14 @@ impl Database {
         Ok(())
     }
 
+    pub fn set_portable(&self, id: i64, portable: bool, mount_point: Option<&str>) -> SqlResult<()> {
+        self.conn.execute(
+            "UPDATE appimages SET is_portable = ?2, mount_point = ?3 WHERE id = ?1",
+            params![id, portable as i32, mount_point],
+        )?;
+        Ok(())
+    }
+
     // --- Launch statistics ---
 
     pub fn get_top_launched(&self, limit: i32) -> SqlResult<Vec<(String, u64)>> {