feat: add configurable lifecycle_card_position setting

[jsenecal]

Summary

Add lifecycle_card_position setting to control the position of Hardware Lifecycle Info cards on Device, Module, DeviceType, and ModuleType detail pages.

Note: This PR is built on top of #127 and should be merged after it.

Changes

• Add lifecycle_card_position setting (defaults to right_page)
• Refactor template_content.py with BaseLifecycleContent base class to reduce code duplication
• All 4 lifecycle info cards now respect the position setting
• Update README with new configuration option

Configuration

PLUGINS_CONFIG = {
    'netbox_lifecycle': {
        'lifecycle_card_position': 'right_page',  # Options: left_page, right_page, full_width_page
        'contract_card_position': 'right_page',
    },
}

Tests

All 388 existing tests pass.