Add SSL, MDC database, and custom HANA connection parameters

Fixes 'error while parsing protocol' HanaException by supporting
SSL/TLS encryption, Multi-Tenant Database Container (MDC) database
name, and arbitrary additional connection parameters.

- HanaServer model: added DatabaseName, UseSsl, ValidateCertificate,
  AdditionalParams fields + BuildConnectionString() helper
- HanaQueryService: accepts HanaServer directly, uses
  BuildConnectionString() for full parameter support
- AppDbContext: added EnsureSchema() method that uses PRAGMA table_info
  + ALTER TABLE ADD COLUMN to add the new fields to existing SQLite
  databases without losing data (EnsureCreated does not update schema)
- Program.cs: calls EnsureSchema on startup before seeding
- Standorte.razor: server dialog now exposes DatabaseName, UseSsl,
  ValidateCertificate, AdditionalParams with helper texts; test
  connection uses new signature

https://claude.ai/code/session_012heAXNMbbyxqYf2S2HrKLj

TrafagSalesExporter/Services/HanaQueryService.cs

@@ -5,10 +5,10 @@ namespace TrafagSalesExporter.Services;
 
 public class HanaQueryService
 {
-    public List<SalesRecord> GetSalesRecords(string host, int port, string username, string password,
+    public List<SalesRecord> GetSalesRecords(HanaServer server,
         string schema, string tsc, string land, string dateFilter)
     {
-        var connectionString = $"ServerNode={host}:{port};UserName={username};Password={password}";
+        var connectionString = server.BuildConnectionString();
         var result = new List<SalesRecord>();
 
         using var connection = new HanaConnection(connectionString);
@@ -32,9 +32,9 @@ public class HanaQueryService
         return result;
     }
 
-    public void TestConnection(string host, int port, string username, string password)
+    public void TestConnection(HanaServer server)
     {
-        var connectionString = $"ServerNode={host}:{port};UserName={username};Password={password}";
+        var connectionString = server.BuildConnectionString();
         using var connection = new HanaConnection(connectionString);
         connection.Open();
     }