Refactor methods for Telegram Premium and Stars giveaways

- Added new methods for handling giveaways: `giveaway_premium` and `giveaway_stars`.
- Refactored existing purchase methods into separate files: `purchase_premium.py` and `purchase_stars.py`.
- Removed old premium and stars methods from the codebase.
- Updated `__init__.py` to include new giveaway methods in the public API.
- Introduced new result types for giveaways: `PremiumGiveawayResult` and `StarsGiveawayResult`.
- Updated constants for new giveaway pages.
- Enhanced error handling for configuration and user validation in giveaway methods.
- Updated tests to cover new functionality and refactored existing tests to match new method locations.

examples/purchase_premium.py

@@ -33,7 +33,7 @@ async def main() -> None:
             print(f"Invalid argument: {e}")
             return
 
-    print(f"{result.months} months of Premium successfully sent to {result.username} | tx: {result.transaction_id}")
+    print(f"{result.amount} months of Premium successfully sent to {result.username} | tx: {result.transaction_id}")
 
 
 if __name__ == "__main__":

examples/purchase_stars.py

@@ -19,7 +19,7 @@ COOKIES = {
 }
 
 USERNAME = "@username"
-AMOUNT = 500  # 50–1 000 000
+AMOUNT = 500  # 50 to 1 000 000 stars, integer
 
 
 async def main() -> None:
@@ -33,7 +33,7 @@ async def main() -> None:
             print(f"Invalid argument: {e}")
             return
 
-    print(f"{result.stars} Stars successfully sent to {result.username} | tx: {result.transaction_id}")
+    print(f"{result.amount} Stars successfully sent to {result.username} | tx: {result.transaction_id}")
 
 
 if __name__ == "__main__":

examples/topup_ton.py

@@ -19,7 +19,7 @@ COOKIES = {
 }
 
 USERNAME = "@username"
-AMOUNT = 10  # TON, integer — 1–1 000 000 000
+AMOUNT = 10  # TON, integer — 1 to 1 000 000 000
 
 
 async def main() -> None: