feat: multi-annotation hover tooltip (#234)

[Moomboh]

Summary

Closes #234.

Lets users opt extra annotation features into the hover tooltip alongside the primary (legend-defining) annotation.

Dropdown UI (protspace-annotation-select)

• Filled primary indicator dot on the currently selected row.
• Small (i) toggle button on every non-primary row. Click flips that annotation in/out of the hover tooltip; native title provides the help text ("Show in hover tooltip" / "Hide from hover tooltip"). aria-pressed reflects state.
• Toggle dispatches tooltip-annotation-toggle (separate from annotation-select); the row label still selects the primary.

Hover tooltip

• TooltipView now carries an ordered blocks[] array. Each AnnotationBlock has its own key, displayValues, numericValue/numericType, scores, evidence.
• The primary annotation renders first, then any extras in dropdown-add order — each gets the full treatment (header, scores/evidence column, raw numeric row).

State + persistence

• New ?tooltip=foo,bar URL param (comma-separated). Parser dedupes, drops the primary, drops names not in the dataset, marks anything off for normalization on next URL write.
• Dataset-scoped localStorage (protspace:tooltip-annotations:<hash>) seeded on dataset load when the URL does not pin a value; kept in sync afterwards via the existing view-change subscription.
• Promoting an extra annotation to primary drops it from the extras (no double-render).

Test coverage

• 11 new url-state tests, 5 localStorage-store tests, 6 component tests for the dropdown UI, multi-annotation tests for buildTooltipView.
• New Playwright spec multi-annotation-tooltip.spec.ts (3 tests) covers the dropdown indicator/toggle, URL writes on toggle, and round-trip removal — all pass locally.
• Existing 818 + 73 + 243 unit/component tests still pass.

Test plan

• Primary annotation visually distinguished in the dropdown (radio-dot)
• (i) icon toggles tooltip inclusion without changing the primary annotation
• Hover tooltip shows extra blocks for opted-in annotations in stable order
• State persists across reloads (URL + dataset-scoped localStorage)
• Keyboard nav unchanged; aria-pressed + title on (i) for a11y
• Type-check, knip, unit/component tests, docs build (via pre-commit)
• Local Playwright e2e spec for the new dropdown + URL plumbing

🤖 Generated with Claude Code

[tsenoner]

• Ensure that the tooltip uses the available vertical space and does not go outside the bottom if selecting points in the lower area.
• Update the annotation selection toggle icon to be a closed and open eye
• make the numeric value in the tooltip non-bold and simply call it "value" not "raw value"

[Moomboh]

Addressed the three review items:

• (i) → eye icons — the per-row tooltip toggle now uses an open-eye when the annotation is included in the hover tooltip and a closed-eye (slashed) when it isn't (packages/core/src/components/control-bar/annotation-select.ts).
• "Raw value:" → "Value:" (non-bold) — renamed the label and replaced the bold .label styling with new .tooltip-annotation-raw-label / .tooltip-annotation-raw-value classes (both font-weight: normal, muted color) (packages/core/src/components/scatter-plot/protein-tooltip.{ts,styles.ts}). The numeric-binning Playwright test that greps the row was updated accordingly.
• Tooltip overflow at the bottom — scatter-plot.ts now measures the real rendered tooltip height in updated() and uses it for the vertical clamp in _getTooltipStyle() instead of a hardcoded tooltipApproxHeight = 160, so multi-block tooltips on points near the bottom edge stay fully inside the plot viewport.