fix: correct ranking position calculation to show higher scores first

Previously, higher scores were displayed with larger position numbers
(e.g., position 63/63 for highest score). Fixed the position calculation
in both tier and overall rankings by reversing the position calculation
to show higher scores with smaller position numbers (1st, 2nd, etc.).

closes: #187

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Author: unhappychoice

src/scoring/rank_calculator.rs

@@ -24,19 +24,19 @@ impl RankCalculator {
         }
         .to_string();
 
-        let tier_position = same_tier_ranks
-            .iter()
-            .position(|rank| rank.name() == current_rank.name())
-            .unwrap_or(0)
-            + 1;
+        let tier_position = same_tier_ranks.len()
+            - same_tier_ranks
+                .iter()
+                .position(|rank| rank.name() == current_rank.name())
+                .unwrap_or(0);
 
         let tier_total = same_tier_ranks.len();
 
-        let overall_position = all_ranks
-            .iter()
-            .position(|rank| rank.name() == current_rank.name())
-            .unwrap_or(0)
-            + 1;
+        let overall_position = all_ranks.len()
+            - all_ranks
+                .iter()
+                .position(|rank| rank.name() == current_rank.name())
+                .unwrap_or(0);
 
         let overall_total = all_ranks.len();