Validate slippage range (0-100) in buy and sell commands #1

Problem

--slippage accepts any integer with no bounds checking:

• --slippage -5 → formula produces impossible min_tokens_out, guaranteed on-chain rejection
• --slippage 999 → large negative integer → struct.error crash with Python traceback

Fix

Add validation in src/pumpfun_cli/commands/trade.py in both buy() and sell(), after _validate_mint():

if slippage < 0 or slippage > 100:
    error("Slippage must be between 0 and 100.", hint="Got: {slippage}")

Files to change

• src/pumpfun_cli/commands/trade.py — add validation in buy() and sell()
• tests/test_commands/test_trade_cmd.py — add tests for out-of-range slippage

How to test

uv run pytest tests/test_commands/test_trade_cmd.py -v