feat(#13): register CalendarSubscriptionService and add public /calendar/{token}.ics endpoint

src/GmRelay.Web/Program.cs

@@ -23,6 +23,7 @@ builder.AddNpgsqlDataSource("gmrelaydb");
 builder.Services.AddSingleton<TelegramAuthService>();
 builder.Services.AddSingleton<ISessionStore, SessionService>();
 builder.Services.AddScoped<AuthorizedSessionService>();
+builder.Services.AddScoped<CalendarSubscriptionService>();
 
 // Add Bot Client
 builder.Services.AddSingleton<ITelegramBotClient>(sp =>
@@ -145,6 +146,24 @@ app.MapPost("/auth/logout", async (HttpContext context) =>
     return Results.Redirect("/");
 });
 
+// Public calendar subscription endpoint (no auth required)
+app.MapGet("/calendar/{token}.ics", async (
+    string token,
+    CalendarSubscriptionService service,
+    CancellationToken ct) =>
+{
+    try
+    {
+        var ics = await service.GetIcsAsync(token, ct);
+        var bytes = System.Text.Encoding.UTF8.GetBytes(ics);
+        return Results.File(bytes, "text/calendar", "schedule.ics");
+    }
+    catch (SubscriptionNotFoundException)
+    {
+        return Results.NotFound();
+    }
+});
+
 app.Run();
 
 static ClaimsPrincipal CreateTelegramPrincipal(long telegramId, string name)