Scheduled tools pause: UI + run-loop wiring (backend done)

[JoshuaRowePhantom]

Summary

Wire the deferred UI and run-loop parts of the scheduled-tools pause / stop-all feature from docs/design/scheduled-tools.md. The deterministic backend is already implemented and merged.

Already done (backend)

• ScheduledToolHost: host-pause gate (user-computer-profile.scheduled-tools-paused), per-relationship paused skip, due-checks against tool-relationship.last-started (stamped before each run), and StopAllRunningExecutions cancellation.
• ScheduledToolPauseStateService: persist/read the pause flag, change event, and stop-all delegation.
• Schema: tool-relationship.paused + last-started, user-computer-profile.scheduled-tools-paused.
• Deterministic tests for the above.

Remaining scope (this issue)

• Periodic ScheduledToolRunner + MainWindowViewModel start/stop wiring (immediate run on startup, fixed poll interval, serialized non-overlapping invocations, cancel on shutdown).
• Pause-icon binding on the clock / scheduled-tools button (pause icon when paused).
• Boolean left-right toggle editor control (shared with entity-editor clone).
• tool-relationship entity-type view fields: editable paused toggle + visible last-started.

Acceptance

• The runner starts on workspace open and stops on shutdown without overlapping runs.
• The main-window button shows the pause icon whenever paused.
• Per-relationship and host pause toggles edit through the boolean toggle control and persist.