feat(api): add api.Ptr helper for optional scalar fields

Telegram's optional int/bool/float fields are pointers so callers can
explicitly send false or 0 to override a chat default — distinct from
'absent', which uses the chat default. The pointer construction has been
ergonomically painful:

  photoLimit := int64(5)
  Limit: &photoLimit

api.Ptr[T any](v T) *T collapses that to a single line:

  Limit: api.Ptr[int64](5)
  DisableNotification: api.Ptr(true)

Pointers stay because the explicit-zero distinction matters for fields
like DisableNotification, ProtectContent, and getUpdates.Offset where
sending 0 / false explicitly is semantically different from omitting
the field.

README.md

@@ -141,6 +141,25 @@ Run any example: `TELEGRAM_BOT_TOKEN=xxx go run ./examples/<name>`
 | | [`polls`](examples/polls) | `sendPoll` and answer tally |
 | | [`payments`](examples/payments) | Invoice → pre-checkout → success |
 
+## Optional fields
+
+Telegram marks many fields as optional. For optional **scalars** (int, bool, float) we use pointers so you can explicitly send `false` or `0` when the wire format needs to override a chat default. The `api.Ptr` helper keeps that ergonomic:
+
+```go
+api.SendMessage(ctx, bot, &api.SendMessageParams{
+    ChatID:              api.ChatIDFromInt(chatID),
+    Text:                "hi",
+    DisableNotification: api.Ptr(true),     // type inferred
+})
+
+api.GetUserProfilePhotos(ctx, bot, &api.GetUserProfilePhotosParams{
+    UserID: userID,
+    Limit:  api.Ptr[int64](5),              // explicit type for untyped literals
+})
+```
+
+Optional structs and slices are already nullable in Go — no helper needed.
+
 ## Reference docs
 
 Full API reference is auto-generated from source comments and lives in [`docs/reference/`](docs/reference/README.md) — browse package by package on GitHub, or read it rendered at [go-telegram.raczylo.com](https://go-telegram.raczylo.com/) and [pkg.go.dev](https://pkg.go.dev/github.com/lukaszraczylo/go-telegram).

api/ptr.go

@@ -0,0 +1,16 @@
+package api
+
+// Ptr returns a pointer to v. Useful for optional scalar fields where
+// the wire format must distinguish absent (nil) from an explicit zero
+// value (e.g. DisableNotification: api.Ptr(false) to override the
+// chat default).
+//
+// For untyped literals, supply the type parameter explicitly:
+//
+//	Limit: api.Ptr[int64](5)
+//
+// For already-typed values, type inference handles it:
+//
+//	var n int64 = 5
+//	Limit: api.Ptr(n)
+func Ptr[T any](v T) *T { return &v }

api/ptr_test.go

@@ -0,0 +1,28 @@
+package api_test
+
+import (
+	"testing"
+
+	"github.com/lukaszraczylo/go-telegram/api"
+)
+
+func TestPtr(t *testing.T) {
+	if got := api.Ptr[int64](5); got == nil || *got != 5 {
+		t.Fatalf("Ptr[int64](5) = %v, want *5", got)
+	}
+	if got := api.Ptr(false); got == nil || *got != false {
+		t.Fatalf("Ptr(false) = %v, want *false", got)
+	}
+	if got := api.Ptr("hello"); got == nil || *got != "hello" {
+		t.Fatalf("Ptr(\"hello\") = %v, want *\"hello\"", got)
+	}
+
+	n := int64(42)
+	got := api.Ptr(n)
+	if got == nil || *got != 42 {
+		t.Fatalf("Ptr(n) = %v, want *42", got)
+	}
+	if got == &n {
+		t.Fatalf("Ptr should copy, not alias caller's variable")
+	}
+}

docs/reference/api.md

@@ -59,6 +59,7 @@ Package api contains the Telegram Bot API object types and method wrappers, gene
 - [func LogOut\(ctx context.Context, b \*client.Bot, p \*LogOutParams\) \(bool, error\)](<#LogOut>)
 - [func PinChatMessage\(ctx context.Context, b \*client.Bot, p \*PinChatMessageParams\) \(bool, error\)](<#PinChatMessage>)
 - [func PromoteChatMember\(ctx context.Context, b \*client.Bot, p \*PromoteChatMemberParams\) \(bool, error\)](<#PromoteChatMember>)
+- [func Ptr\[T any\]\(v T\) \*T](<#Ptr>)
 - [func ReadBusinessMessage\(ctx context.Context, b \*client.Bot, p \*ReadBusinessMessageParams\) \(bool, error\)](<#ReadBusinessMessage>)
 - [func RefundStarPayment\(ctx context.Context, b \*client.Bot, p \*RefundStarPaymentParams\) \(bool, error\)](<#RefundStarPayment>)
 - [func RemoveBusinessAccountProfilePhoto\(ctx context.Context, b \*client.Bot, p \*RemoveBusinessAccountProfilePhotoParams\) \(bool, error\)](<#RemoveBusinessAccountProfilePhoto>)
@@ -1315,6 +1316,28 @@ PromoteChatMember calls the promoteChatMember Telegram Bot API method.
 
 Use this method to promote or demote a user in a supergroup or a channel. The bot must be an administrator in the chat for this to work and must have the appropriate administrator rights. Pass False for all boolean parameters to demote a user. Returns True on success.
 
+<a name="Ptr"></a>
+## func Ptr
+
+```go
+func Ptr[T any](v T) *T
+```
+
+Ptr returns a pointer to v. Useful for optional scalar fields where the wire format must distinguish absent \(nil\) from an explicit zero value \(e.g. DisableNotification: api.Ptr\(false\) to override the chat default\).
+
+For untyped literals, supply the type parameter explicitly:
+
+```
+Limit: api.Ptr[int64](5)
+```
+
+For already\-typed values, type inference handles it:
+
+```
+var n int64 = 5
+Limit: api.Ptr(n)
+```
+
 <a name="ReadBusinessMessage"></a>
 ## func ReadBusinessMessage