feat(frontend): add Linnaean rank icons to taxa display

[frewsxcv]

Summary

• Adds a RankIcon component with monochrome SVG glyphs for each Linnaean rank — stacked bars for phylum and above (1/2/3 = phylum/kingdom/domain), filled dots on the implied polygon for class → species (5/4/3/2/1), hollow or gap-split variants for sub-ranks. Returns null for ranks without a glyph (tribe, super-/infra-, etc.). Uses currentColor so it inherits surrounding text color.
• Surfaces the icons next to rank labels in the taxon detail header, breadcrumb, classification list (ancestors / current / children), and tree panel.

Glyph system based on the artifact: https://claude.ai/public/artifacts/87f5a057-5438-49a2-bf65-39f117f43a4a

Screenshots

Tree panel — every rank from kingdom (Animalia) down through subspecies, each with its distinct glyph. Note that rare/unranked entries (e.g. BOLD:AAA9440, unranked) correctly fall back to text with no icon:

Species page — header reads "● Species" (filled dot), tree on the left shows the full Linnaean chain:

Family page — header reads "▴ Family" (3-dot triangle), and the tree highlights Turdidae with its 23+ child genera each marked with the 2-dot genus glyph:

Test plan

• Visit a species page — header shows the filled-dot icon next to "Species".
• Visit a family page — header shows the 3-dot triangle next to "Family".
• Tree panel shows the correct glyph for every rank (kingdom, phylum, class, order, family, genus, species, subspecies).
• Unrecognised ranks (unranked, BOLD identifiers) render as text without a broken icon.
• Manual: confirm icons remain readable in dark mode (currentColor should follow text color).

Notes

• TaxonDetail.tsx is also updated for consistency, but it is currently dead code — the live taxon route renders TaxonExplorer (which uses TaxonDetailPanel + TaxonTreePanel).