Remove /start command as name doesn't match functionality, and fix
command parsing to handle @botname suffix for group chat compatibility.
Changes:
- Remove handle_start function and registration
- Remove /start from help command list
- Remove test_start_command_content test
- Strip @botname suffix from commands (e.g., /help@mybot → help)
Rationale:
- /start command name implies bot initialization, but it was just
showing help text (duplicate of /help)
- Better to have one clear /help command
- @botname suffix handling needed for group chats
Test:
- 27 tests pass (1 removed, 1 added for @botname handling)
- All existing functionality preserved
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
