Run mode toolbar items: Pause (⌘.), End Encounter, Fear Tracker

[gwillish]

Per ADR-0047 and redesign-plan.md M6d. Depends on #136.

Toolbar content zone items contributed when AppWindowMode == .runningEncounter:

• Pause (⌘.) — calls session.pause(), saves, returns to prep mode
• End Encounter (no shortcut — destructive) — confirmation required; clears session
• Fear Tracker button (FearTrackerButton — existing) — popover

These are the authoritative Pause/End controls. Any Pause/End UI in RunnerListPanel headers should be removed (see #134).

All buttons have .help("…") tooltips.