Add manual wakelock controls

[NightHammer1000]

What changed

• add independent tray-menu controls to keep the display awake or prevent standby
• hold documented Windows power requests and release them on toggle-off or process exit
• refresh the tray status immediately and preserve accurate checkmarks on errors
• document the controls and bump the crate version to 0.2.0

Why

WakeWatch previously only reported wakelocks. These controls let a user deliberately create display or standby wakelocks from the same tray menu.

Validation

• cargo fmt --all -- --check
• cargo clippy --all-targets --all-features -- -D warnings
• cargo test --all-targets (45 passed)
• cargo build --release