feat: show connected device battery on Home

[highdeftant]

Feature

Show the connected device battery percentage in the Home screen header.

Behavior

• Display the percentage and a battery/charging icon when a device is connected and battery data is available.
• Use charging styling/icon when charging.
• Hide the indicator when no device is connected or battery data is unavailable.
• Reuse the existing AppState device battery state; do not add a second data path.
• Verify on the isolated preview build without modifying production app data.

[highdeftant]

Scope clarification: treat this as a compact connected-wearable status indicator, not only a battery label.

Proposed Home header affordance:

• generic wearable/watch-shaped icon (not the WHOOP trademark/logo)
• small connection-status dot
• battery percentage or battery icon when available
• charging state represented by a bolt
• disconnected/unavailable state remains visible but clearly muted, rather than disappearing silently
• tap opens device settings/details

Reuse existing AppState/DeviceState and battery fields; no new database schema or BLE pipeline.

[gentbot]

Doesn't this already exist in the top left section? In the smaller font under the greeting and name it shows when last synced and the battery percentage, I haven't look at the state when charging but it might already be there, or were you suggesting something in addition?