feat(component-family): Canvas runtime activity & time overlays — run timeline, strip, pulses

[bntvllnt]

Goal

Create the canvas runtime activity and time overlay family so dashboard widgets become ambient spatial execution surfaces.

Minimum serious v0 ownership

• RunTimeline
• BottomActivityStrip
• StickyMetric
• MetricCluster
• HeatOverlay
• AlertPulse
• StateBadgeOverlay
• TimelineScrubber
• PlaybackGhost
• ThresholdRing

Why

This is the bridge from dashboard KPIs and activity feeds to a calm spatial control plane for tasks, runs, outputs, and system state.

Explicit non-duplicates

This family must not duplicate or merely re-skin:

• MetricGauge
• ActivityHeatmap
• ActivityLog
• LiveFeed
• financial charts (CandlestickChart, MarketTreemap, SparklineGrid)
• timeline family issues (#32, #33, #34, #35, #63, #64) — those are standalone timeline components; this family is runtime/time navigation inside the canvas
• AI Artifact / Canvas issue #56 — artifact viewing stays separate; this family should connect runs and time context to artifacts rather than duplicate the viewer

Acceptance criteria

• define the run timeline for execution history, current state, and transitions
• define the bottom activity strip as the lowest-noise live execution surface
• define how metrics, alerts, and time state attach to objects, groups, and regions
• define visual hierarchy between ambient overlays and primary object content
• define time-scrubbing semantics for canvas state playback
• keep the family useful for ops, AI, analytics, and workflow products