feat(shutdown): added functionality to shutdown surge when all downloads are done

[junaid2005p]

…ads are done

Greptile Summary

This PR adds automatic system shutdown after all downloads finish. The main changes are:

• A configurable auto-shutdown setting and TUI status indicator.
• Cross-platform shutdown and sleep-inhibitor controllers.
• Download-state reconciliation for completion, deletion, purge, and enqueue events.
• Delayed shutdown retries with sleep prevention during backoff.
• Tests for completion, paused downloads, deletion, settings, and retries.

Confidence Score: 5/5

This looks safe to merge.

The Windows inhibitor now releases execution state on the thread that acquired it. Download removal paths now refresh auto-shutdown state. Failed shutdowns retain sleep prevention and retry after a delay.

No blocking issues remain in the changed paths.

T-Rex Logs

What T-Rex did

• The baseline focused test run for TestAutoShutdown completed successfully (exit code 0).
• The race-enabled test run for TestAutoShutdown completed successfully (exit code 0).
• A separate captured command enumerated the fake Shutdown/AcquireInhibitor seam with counter assertions and all six tests executed.

_{Ran code and verified through T-Rex}

Important Files Changed

Filename	Overview
internal/power/power_windows.go	Keeps Windows execution-state acquisition and release on the same locked OS thread.
internal/tui/power.go	Manages auto-shutdown arming, inhibition, shutdown execution, and delayed retries.
internal/tui/update_events.go	Reconciles auto-shutdown after download events and handles shutdown retry messages.
internal/tui/update_dashboard.go	Reconciles auto-shutdown after downloads are removed from the dashboard.
internal/tui/update_modals.go	Releases the power inhibitor on quit or restart and reconciles purge actions.
internal/tui/power_test.go	Tests shutdown triggering, blocking states, setting changes, deletion, and retry behavior.

_{Reviews (5): Last reviewed commit: "tui: keep power inhibitor during auto-sh..." | Re-trigger Greptile}

[github-actions]

Binary Size Analysis

⚠️ Size Increased

Version	Human Readable	Raw Bytes
Main	17.06 MB	17887524
PR	17.57 MB	18428196
Difference	528.00 KB	540672

[SuperCoolPencil]

icon not centered :(

[junaid2005p]

icon not centered :(

noted. will fix.