fix(web): hovering a commit marker opens its commit card again - #2578

🟢 Confidence 8/10 · likely safe to merge. The marker card is wired the way the existing commit card is, but its own open path and row rendering ship untested.
_{1 warning −1 · tests partial −1 · risk low}

Hovering a deploy marker now opens a card listing the commits first seen in that bucket, wired on the service Overview grid, the API responses chart and the release detail grid. The wiring follows the existing commit-card pattern; the gap is that the card's own behaviour is not pinned by a test.

• markerCardBody renders a marker group's commits in a shared HoverCard
• markersOverlay takes a page card and binds label or dash triggers to it
• markerShas resolves every commit a card lists, capped at MARKER_CARD_COMMITS
• The marker layer moves beside the chart on the grid, API tab and release grid

Findings

Add a scene test: hover a grid marker label, resolve `WaitHoverDelay` and `MountHoverCard`, then assert the card lists every commit of the merged group and stops at `MARKER_CARD_COMMITS` with `+N more`.

_{6e97b75 · Reply "won't fix" to dismiss a finding, or mention @maple-review-bot to ask about one.}