perf: increase DB timeout to 120s, reduce retries to 3 with longer delay

Raspberry Pi PostgreSQL is I/O constrained. 60s timeout was too short
for concurrent writes during heavy recording sessions, causing timeout +
retry causing duplicate key violations.

- CommandTimeout: 60s -> 120s
- maxRetryCount: 5 -> 3
- maxRetryDelay: 10s -> 15s

Co-Authored-By: Claude Opus 4.8 noreply@anthropic.com

src/LiveRecorder.WebApi/Program.cs

@@ -132,7 +132,7 @@ if (connectionStringBuilder.Timeout <= 0)
 
 if (connectionStringBuilder.CommandTimeout <= 0)
 {
-    connectionStringBuilder.CommandTimeout = 60;
+    connectionStringBuilder.CommandTimeout = 120;
 }
 
 if (connectionStringBuilder.KeepAlive <= 0)
@@ -146,8 +146,8 @@ builder.Services.AddDbContext<LiveRecorderDbContext>(options =>
         npgsql.MigrationsAssembly(typeof(LiveRecorderDbContext).Assembly.FullName);
         npgsql.CommandTimeout(connectionStringBuilder.CommandTimeout);
         npgsql.EnableRetryOnFailure(
-            maxRetryCount: 5,
-            maxRetryDelay: TimeSpan.FromSeconds(10),
+            maxRetryCount: 3,
+            maxRetryDelay: TimeSpan.FromSeconds(15),
             errorCodesToAdd: null);
     }));