feat(ui): draggable edges on trace overview minimap

[daharoni]

Summary

• Adds resize handles to the zoom rectangle on the trace-card minimap: dragging the left/right edge moves just that boundary while the opposite side stays fixed.
• Body-drag / click-to-recenter behavior is unchanged.
• Small darker-blue grip with a white notch is drawn on each visible edge, and the cursor switches to ew-resize on hover for discoverability.
• Change is in the shared TraceOverview component, so both CaTune and CaDecon pick it up without any call-site changes.

Implementation notes:

• Hit-testing treats an edge as grabbable only when its time boundary actually falls within the row under the cursor — prevents the clipped x=0 / x=width sides on intermediate rows of a multi-row zoom from being mistaken for handles.
• Drags clamp to [0, totalDuration] with a one-sample minimum gap so the window can't invert or collapse.

Test plan

• Hover near the edges of the blue rectangle — cursor becomes ew-resize, grip is visible.
• Drag left edge: zoomStart moves, zoomEnd fixed.
• Drag right edge: zoomEnd moves, zoomStart fixed.
• Dragging one edge past the other clamps (no inversion).
• Clicking/body-dragging inside the rect still pans the window as before.
• Clicking outside the rect still recenters the window.
• Multi-row zoom: grip only shows on the row containing the actual boundary (not on clipped edges of rows in between).
• Verify in both CaTune and CaDecon trace inspectors.

🤖 Generated with Claude Code

[daharoni]

Added nice little draggable edges to the trace viewer: