[khiet]

Summary

The Instrument panel's tyre gauge now draws the own kart from behind, as the chase camera sees it, instead of from above (ADR 0105, take 3 of docs/mockups/coin-and-tyre-gauge-variations.html).

 <div data-instrument="tyre" data-tyre-wear="good|warn|bad">
-  kartFromAbove(livery)        # 60x92: four tyres, wings front and back
+  kartFromBehind(livery)       # 72x58: rear wing, two rears, tub, halo, hair
     tyreBlock x2               # was tyreFromAbove x4; keeps data-tyre-corner
   <span data-tyre-percent>100%</span>

• Only the two rears carry data-tyre-corner, so they take the band's tone. Tyre life is one number, so hiding the fronts loses nothing.
• The percentage and data-tyre-wear are unchanged. The gauge SVG widens from --hud * 3.6 to 4.2, as in the mockup.
• docs/style-guide.html now draws the kart from behind and shows the gauge in all three bands. The from-above rule and tyre life in docs/GLOSSARY.md now say "from behind".

Evidence

• Before: the gauge drew four data-tyre-corner tyres around a kart seen from above.
  After: the panel was staged headless at tyre life 100, 45 and 12 for liveries 1, 4 and 6. Bands read good/warn/bad, both rears filled green/yellow/red, and each livery's hair colour was drawn.

it "draws the own kart from behind, so only its two rear tyres take the band's tone"
  count [data-tyre-corner] in the tyre gauge == 2    # was 4: red, now green
it "paints slot N's ... tyre gauge, not slot M's"
  gauge fills include primary, secondary, accent and the driver's hair colour

pnpm test: 1195 passed. Biome and typecheck are clean.

Screenshots:

Gauge: good, warn, bad (livery 1), then liveries 4 and 6	Style guide entry in all three bands

Merge Danger

Door: two-way

A drawing swap. Reverting the commit restores the kart from above.

Blast Radius: cosmetic

Only the tyre gauge icon and its width in the speed cluster change. The gauge is 0.6 --hud wider, which nudges the BOX, STOP and RAIN plates that sit off the cluster's right edge.

Closes #352