Phase 1012: Live event markers + click-to-details on FastSense/FastSenseWidget (#77)

Phase 1012 — Live event markers + click-to-details on FastSense/FastSenseWidget

Extension of v2.0 Tag-Based Domain Model. Tagged as v2.0.1.

Core deliverables:
- Event.IsOpen logical property + EventStore.closeEvent(id, endTime, finalStats) in-place update
- MonitorTag rising-edge open emission with running Peak/Min/Max/Mean/RMS/Std in cache_.openStats_; falling edge calls closeEvent
- TrendMiner-style per-event markers — white circular badge + soft drop shadow + severity-colored '!' glyph; severity→color (info/warn/alarm)
- Click-to-details popup as standalone figure (OS-native drag/close), light theme, section-grouped uitable with resize-aware columns, editable Notes textarea with Save that mutates Event.Notes and calls EventStore.save() for disk persistence
- FastSenseWidget.ShowEventMarkers + EventStore properties; onLiveTick marker diff against LastEventIds_/LastEventOpen_/LastEventSeverity_
- New demo: examples/example_event_markers.m (two-sensor pump+motor with severity-colored markers sharing one disk-backed EventStore)

Tests: TestEventIsOpen, TestMonitorTagOpenEvent, TestFastSenseEventClick, TestFastSenseWidgetEventMarkers + Octave mirrors all green. Pitfall-10 zero-event render regression gate: -4.5% / -1.3% (PASS).

Merge conflicts resolved (3 files): FastSenseWidget.m (4 chunks combined additively with main's LiveViewMode/autoScaleY_/formatTimeAxis_), FastSense.m + DashboardTheme.m auto-merged cleanly. Planning artifacts kept local per main's PR #61 gitignore policy.

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Author: HanSur94