feat: Auth-Tokens in SQLite persistieren statt in-memory

Tokens überleben jetzt App-Restarts. AuthService schreibt/liest
Tokens aus einer 'tokens'-Tabelle in der SQLite-DB.
Logout (RevokeToken) funktioniert weiterhin korrekt.

Program.cs

@@ -13,8 +13,9 @@ builder.Services.AddHttpClient();
 
 var dataDir = Path.Combine(AppContext.BaseDirectory, "data");
 
-var authService = new AuthService();
-var dbService = new DatabaseService(Path.Combine(dataDir, "gott.db"));
+var dbPath = Path.Combine(dataDir, "gott.db");
+var authService = new AuthService(dbPath);
+var dbService = new DatabaseService(dbPath);
 dbService.EnsureDefaultUser(authService);
 
 builder.Services.AddSingleton(authService);

Services/AuthService.cs

@@ -1,13 +1,40 @@
 using System;
-using System.Collections.Concurrent;
 using System.Security.Cryptography;
 using System.Text;
+using Dapper;
+using Microsoft.Data.Sqlite;
 
 namespace Gott.Services;
 
 public class AuthService
 {
-    private readonly ConcurrentDictionary<string, string> _tokens = new(); // token -> userId
+    private readonly string _connectionString;
+
+    public AuthService(string dbPath)
+    {
+        _connectionString = $"Data Source={dbPath}";
+        InitializeTable();
+    }
+
+    private SqliteConnection CreateConnection()
+    {
+        var conn = new SqliteConnection(_connectionString);
+        conn.Open();
+        return conn;
+    }
+
+    private void InitializeTable()
+    {
+        using var conn = CreateConnection();
+        conn.Execute(@"
+            CREATE TABLE IF NOT EXISTS tokens (
+                token      TEXT NOT NULL PRIMARY KEY,
+                user_id    TEXT NOT NULL,
+                created_at TEXT NOT NULL
+            );
+            CREATE INDEX IF NOT EXISTS idx_tokens_user ON tokens(user_id);
+        ");
+    }
 
     public string HashPassword(string password)
     {
@@ -23,19 +50,25 @@ public class AuthService
     public string CreateToken(string userId)
     {
         var token = Convert.ToHexStringLower(RandomNumberGenerator.GetBytes(32));
-        _tokens[token] = userId;
+        using var conn = CreateConnection();
+        conn.Execute(
+            "INSERT INTO tokens (token, user_id, created_at) VALUES (@token, @userId, @now)",
+            new { token, userId, now = DateTime.UtcNow.ToString("o") });
         return token;
     }
 
     public string ValidateToken(string token)
     {
         if (string.IsNullOrEmpty(token)) return null;
-        return _tokens.TryGetValue(token, out var userId) ? userId : null;
+        using var conn = CreateConnection();
+        return conn.QuerySingleOrDefault<string>(
+            "SELECT user_id FROM tokens WHERE token = @token", new { token });
     }
 
     public void RevokeToken(string token)
     {
-        if (!string.IsNullOrEmpty(token))
-            _tokens.TryRemove(token, out _);
+        if (string.IsNullOrEmpty(token)) return;
+        using var conn = CreateConnection();
+        conn.Execute("DELETE FROM tokens WHERE token = @token", new { token });
     }
 }