fix(external-system-gateway): resolve ExternalSystemGateway-011 — name-keyed repository lookups replace fetch-all-then-filter on the call hot path

src/ScadaLink.ConfigurationDatabase/Repositories/ExternalSystemRepository.cs

@@ -16,6 +16,12 @@ public class ExternalSystemRepository : IExternalSystemRepository
     public async Task<ExternalSystemDefinition?> GetExternalSystemByIdAsync(int id, CancellationToken cancellationToken = default)
         => await _context.Set<ExternalSystemDefinition>().FindAsync(new object[] { id }, cancellationToken);
 
+    // ExternalSystemGateway-011: genuine name-keyed query (server-side WHERE) so the
+    // gateway's hot-path resolution does not fetch every system and filter in memory.
+    public async Task<ExternalSystemDefinition?> GetExternalSystemByNameAsync(string name, CancellationToken cancellationToken = default)
+        => await _context.Set<ExternalSystemDefinition>()
+            .FirstOrDefaultAsync(s => s.Name == name, cancellationToken);
+
     public async Task<IReadOnlyList<ExternalSystemDefinition>> GetAllExternalSystemsAsync(CancellationToken cancellationToken = default)
         => await _context.Set<ExternalSystemDefinition>().ToListAsync(cancellationToken);
 
@@ -34,6 +40,13 @@ public class ExternalSystemRepository : IExternalSystemRepository
     public async Task<ExternalSystemMethod?> GetExternalSystemMethodByIdAsync(int id, CancellationToken cancellationToken = default)
         => await _context.Set<ExternalSystemMethod>().FindAsync(new object[] { id }, cancellationToken);
 
+    // ExternalSystemGateway-011: genuine name-keyed query scoped to the parent system.
+    public async Task<ExternalSystemMethod?> GetMethodByNameAsync(int externalSystemId, string methodName, CancellationToken cancellationToken = default)
+        => await _context.Set<ExternalSystemMethod>()
+            .FirstOrDefaultAsync(
+                m => m.ExternalSystemDefinitionId == externalSystemId && m.Name == methodName,
+                cancellationToken);
+
     public async Task<IReadOnlyList<ExternalSystemMethod>> GetMethodsByExternalSystemIdAsync(int externalSystemId, CancellationToken cancellationToken = default)
         => await _context.Set<ExternalSystemMethod>().Where(m => m.ExternalSystemDefinitionId == externalSystemId).ToListAsync(cancellationToken);
 
@@ -52,6 +65,11 @@ public class ExternalSystemRepository : IExternalSystemRepository
     public async Task<DatabaseConnectionDefinition?> GetDatabaseConnectionByIdAsync(int id, CancellationToken cancellationToken = default)
         => await _context.Set<DatabaseConnectionDefinition>().FindAsync(new object[] { id }, cancellationToken);
 
+    // ExternalSystemGateway-011: genuine name-keyed query (server-side WHERE).
+    public async Task<DatabaseConnectionDefinition?> GetDatabaseConnectionByNameAsync(string name, CancellationToken cancellationToken = default)
+        => await _context.Set<DatabaseConnectionDefinition>()
+            .FirstOrDefaultAsync(c => c.Name == name, cancellationToken);
+
     public async Task<IReadOnlyList<DatabaseConnectionDefinition>> GetAllDatabaseConnectionsAsync(CancellationToken cancellationToken = default)
         => await _context.Set<DatabaseConnectionDefinition>().ToListAsync(cancellationToken);