Profil-Seite: Anzeigename, Passwort ändern, Persona (ersetzt USER.md)

- Neuer Menüpunkt 'Mein Profil' statt 'Logout'
- Profil-Page: Anzeigename, Persona (Freitext), Passwort ändern, Logout
- ProfileEndpoint: GET/PUT /api/profile, PUT /api/profile/password
- User-Persona im System-Prompt statt USER.md (Fallback: Anzeigename/Username)
- SystemPromptBuilder: dataDir-Parameter entfernt, userPersona-Parameter hinzugefügt
- DB-Migration: persona-Spalte in users-Tabelle

Endpoints/ProfileEndpoint.cs

@@ -0,0 +1,96 @@
+using System.Text.Json;
+using Gott.Extensions;
+using Gott.Services;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Routing;
+
+namespace Gott.Endpoints;
+
+public static class ProfileEndpoint
+{
+    public static void MapProfileEndpoints(this WebApplication app)
+    {
+        app.MapGet("/api/profile", HandleGet);
+        app.MapPut("/api/profile", HandleUpdate);
+        app.MapPut("/api/profile/password", HandlePasswordChange);
+    }
+
+    private static async System.Threading.Tasks.Task HandleGet(HttpContext ctx, DatabaseService db)
+    {
+        var userId = ctx.GetUserId();
+        var user = await db.GetUser(userId);
+        if (user == null)
+        {
+            ctx.Response.StatusCode = 404;
+            await ctx.Response.WriteAsJsonAsync(new { error = "User not found" });
+            return;
+        }
+
+        await ctx.Response.WriteAsJsonAsync(new
+        {
+            userId = user.UserId,
+            username = user.Username,
+            displayName = user.DisplayName,
+            persona = user.Persona,
+            isAdmin = user.IsAdmin
+        });
+    }
+
+    private static async System.Threading.Tasks.Task HandleUpdate(HttpContext ctx, DatabaseService db)
+    {
+        var userId = ctx.GetUserId();
+        var body = await JsonSerializer.DeserializeAsync<JsonElement>(ctx.Request.Body);
+
+        var displayName = body.TryGetProperty("displayName", out var dn) ? dn.GetString() : null;
+        var persona = body.TryGetProperty("persona", out var p) ? p.GetString() : null;
+
+        await db.UpdateUserProfile(userId, displayName, persona);
+
+        var user = await db.GetUser(userId);
+        await ctx.Response.WriteAsJsonAsync(new
+        {
+            userId = user.UserId,
+            username = user.Username,
+            displayName = user.DisplayName,
+            persona = user.Persona,
+            isAdmin = user.IsAdmin
+        });
+    }
+
+    private static async System.Threading.Tasks.Task HandlePasswordChange(HttpContext ctx, DatabaseService db, AuthService auth)
+    {
+        var userId = ctx.GetUserId();
+        var body = await JsonSerializer.DeserializeAsync<JsonElement>(ctx.Request.Body);
+
+        var currentPassword = body.TryGetProperty("currentPassword", out var cp) ? cp.GetString() : null;
+        var newPassword = body.TryGetProperty("newPassword", out var np) ? np.GetString() : null;
+
+        if (string.IsNullOrEmpty(currentPassword) || string.IsNullOrEmpty(newPassword))
+        {
+            ctx.Response.StatusCode = 400;
+            await ctx.Response.WriteAsJsonAsync(new { error = "Aktuelles und neues Passwort erforderlich" });
+            return;
+        }
+
+        if (newPassword.Length < 4)
+        {
+            ctx.Response.StatusCode = 400;
+            await ctx.Response.WriteAsJsonAsync(new { error = "Passwort muss mindestens 4 Zeichen lang sein" });
+            return;
+        }
+
+        var user = await db.GetUser(userId);
+        if (user == null || !auth.VerifyPassword(currentPassword, user.PasswordHash))
+        {
+            ctx.Response.StatusCode = 401;
+            await ctx.Response.WriteAsJsonAsync(new { error = "Aktuelles Passwort ist falsch" });
+            return;
+        }
+
+        var newHash = auth.HashPassword(newPassword);
+        await db.UpdateUserPassword(userId, newHash);
+
+        await ctx.Response.WriteAsJsonAsync(new { ok = true });
+    }
+}