fix(ui): correct macOS pet dragging and tool card layout

[bobleer]

Fix macOS companion pet dragging and tool-card layout problems in the shared UI.

• On macOS, keep pointer capture and move the pet from screen coordinates instead of treating AppKit’s immediately returning native drag call as the gesture lifetime. Convert the window origin to logical coordinates for Retina displays, coalesce position requests, retain the final move on quick release, and prevent WebKit text/image selection. Preserve Windows’ existing drag adapter and the native path on other platforms.
• Give expanded ambient tool-card headers the same geometry as prominent headers while keeping collapsed traces compact. Use OverflowText for plain action labels, allow header text to shrink, and keep image previews within the available card width.

Validation:

• pnpm run check:web passed with both changes applied.
• 25 focused pet component and drag-adapter tests passed.
• 21 tool-card markup and source-contract tests passed.
• 22 Web UI tool-card integration tests passed; content selectors identify the owning component so nested text components cannot shadow the card summary.
• Focused production-file ESLint passed; pnpm run motion:audit completed (intent inventory).
• Native macOS desktop at 2× scale: a 70-point left drag moved the window 140 physical pixels; a reverse drag returned it to its starting position.

Coverage limits: tool-card checks establish markup and source contracts, not manual visual fidelity. Local macOS desktop was exercised; Windows drag behavior is covered by mocked component/adapter tests. Remote workspace, Remote Control, Peer Device Mode, and Detached Dispatch were not exercised. No commands, wire formats, or persisted fields change.