Add custom card features for lock tile cards

[raman325]

Feature Description

Explore adding custom card features to enhance lock tile cards in Home Assistant dashboards.

Custom card features are small UI widgets that appear at the bottom of tile cards, providing quick-access controls without opening the more-info dialog. They're domain-specific and can be registered for lock entities managed by Lock Code Manager.

Possible Features

• PIN quick-set — Set or clear a PIN directly from the tile card
• Slot toggle — Enable/disable a code slot
• Lock status — Show sync status or condition state inline
• Usage counter — Display remaining uses for a slot

Reference

• HA Custom Card Features Documentation
• Features are registered via customTileFeatures on the window object
• Each feature needs getStubConfig(), getConfigElement(), and setConfig()
• Features receive hass and stateObj for the parent entity

Implementation Notes

• Features are tied to entity domains — would need to register for the lock domain
• Consider which LCM data is accessible from just a lock entity's state (vs. requiring websocket subscription)
• Could complement the existing slot cards rather than replace them