Stable organ chip size, lock page scroll in viewer, hover-identify default, red lesion

[aperson30]

Summary

• Organ chips no longer resize on click. They toggled border-0 / border-2, so a click shrank the chip and shifted every row below it. The 2px border is now always present (.vp-organ-chip) and only its color changes. Applies to organ rows, the Pancreas/Colon/Kidneys group headers, Custom Classes, and the compare viewer.
• Viewer no longer scrolls the whole window. Page scroll is locked while the viewer is mounted and panes get overscroll-behavior: contain, so a wheel tick a pane doesn't consume can't move the layout.
• Hover-to-identify defaults to on. The View menu item still toggles it off. (The eye button now reads as active by default.)
• Pancreatic lesion color [80, 0, 0] (dark maroon) to [240, 10, 10] (bright red).

Test plan

• npx tsc -b clean
• npx vitest run 345/345 pass
• Localhost: click organs in the panel, confirm the chip keeps its size and only the outline color toggles
• Localhost: scroll slices in each pane, including at the first/last slice and over the 3D pane, confirm the window stays put
• Localhost: hover an organ with no tool selected and confirm the name tooltip appears