Bump DIMMED_OPACITY 0.4 -> 0.45 so dimmed outlines/labels stay legible against bg-surface in both themes (dark mode dims already-light mint, the riskier case). Import the constant into StammbaumTree.svelte.test.ts so the node-opacity assertions track it instead of a hard-coded '0.4'. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>