Add similar app recommendations from shared categories

src/core/database.rs

@@ -1869,6 +1869,51 @@ impl Database {
         )
     }
 
+    // --- Similar apps ---
+
+    /// Find AppImages from the user's library that share categories with the given app.
+    pub fn find_similar_apps(
+        &self,
+        categories: &str,
+        exclude_id: i64,
+        limit: i32,
+    ) -> SqlResult<Vec<(i64, String, Option<String>)>> {
+        // Split categories and match any overlap
+        let cats: Vec<&str> = categories.split(';').filter(|s| !s.is_empty()).collect();
+        if cats.is_empty() {
+            return Ok(Vec::new());
+        }
+
+        // Build LIKE conditions for each category
+        let conditions: Vec<String> = cats.iter()
+            .map(|c| format!("categories LIKE '%{}%'", c.replace('\'', "''")))
+            .collect();
+        let where_clause = conditions.join(" OR ");
+
+        let sql = format!(
+            "SELECT id, COALESCE(app_name, filename) AS name, icon_path
+             FROM appimages
+             WHERE id != ?1 AND ({})
+             LIMIT ?2",
+            where_clause
+        );
+
+        let mut stmt = self.conn.prepare(&sql)?;
+        let rows = stmt.query_map(params![exclude_id, limit], |row| {
+            Ok((
+                row.get::<_, i64>(0)?,
+                row.get::<_, String>(1)?,
+                row.get::<_, Option<String>>(2)?,
+            ))
+        })?;
+
+        let mut results = Vec::new();
+        for row in rows {
+            results.push(row?);
+        }
+        Ok(results)
+    }
+
     // --- System modification tracking ---
 
     pub fn register_modification(