fix: improve error handling and type safety

- Replaced 'any' types with proper TypeScript types
- Improved error handling with instanceof checks
- Removed unused imports (calculateExpectedTeamScore)
- Updated error messages to be more descriptive
- Removed deprecated eslint.config.mjs file

src/app/api/tournaments/[id]/games/bulk/route.ts

@@ -4,18 +4,7 @@ import { canManageTournament } from "@/lib/permissions";
 import { getSession } from "@/lib/auth-simple";
 import { calculateTeamElo, calculateTeamEloChange } from "@/lib/elo-utils";
 
-interface GameEntry {
-  round: number
-  table: string
-  player1: string
-  player2: string
-  score1: number
-  player3: string
-  player4: string
-  score2: number
-}
-
-const K_FACTOR = 32;
+const K_FACTOR = 32; // Standard K-factor for Elo calculations
 
 export async function POST(
   request: Request,
@@ -139,15 +128,16 @@ export async function POST(
                 },
               });
             }
-          } catch (error) {
+          } catch {
             // Participant already exists, which is fine
             console.log(`Participant ${player.id} already exists in tournament ${tournamentId}`);
           }
         }
 
         importedCount++;
-      } catch (err: any) {
-        errors.push(`Game ${index + 1}: ${err.message}`);
+      } catch (err: unknown) {
+        const message = err instanceof Error ? err.message : "Unknown error";
+        errors.push(`Game ${index + 1}: ${message}`);
         errorCount++;
       }
     }
@@ -157,10 +147,11 @@ export async function POST(
       errorCount,
       errors: errors.length > 0 ? errors : undefined,
     });
-  } catch (error: any) {
+  } catch (error: unknown) {
     console.error("Bulk game submission error:", error);
+    const message = error instanceof Error ? error.message : "Failed to submit games";
     return NextResponse.json(
-      { error: error.message || "Failed to submit games" },
+      { error: message },
       { status: 500 }
     );
   }