Repaint to jet-black + atomic-tangerine skin, add consultant-special 2×2

Why: the default skin was too warm/neutral and the pyramid + venn never
quite read the way they should. Also prepping for public sharing, so the
example diagrams needed to drop the littlemight-specific copy.

Changes:
- New five-color palette: jet-black ink, atomic-tangerine accent,
  white-smoke paper, blue-slate muted, silver hairlines. Replaces
  warm-stone + rust across every variant + dark-mode tokens.
- Default background is clean paper; dot grid + framed container are
  now opt-in variants (uncomment in template to enable).
- New consultant-special quadrant variant (example-quadrant-consultant.html)
  — 2×2 scenario matrix with named cells, double-ended axes, one focal
  quadrant; house skin, not a separate visual language.
- Pyramid redrawn as a true triangular silhouette with shared edges on
  one slope (stacked polygons on a single triangle outline, no kinks).
- Venn redesigned: dark-fill triple-intersection with white text,
  circle labels moved inside non-overlap lobes, pair-overlap labels
  removed, legend dropped.
- Example content genericized (content site / product timeline /
  content platform instead of littlemight-branded copy).
- Screenshots regenerated at 2× DPI; added quadrant-consultant.png
  (14th diagram in the gallery).
- README: hero-first opener, preserved Why-I-built-it section, UTM
  tags on littlemight + bestself links, palette description updated.

references/type-venn.md

@@ -5,11 +5,11 @@
 ## Layout conventions
 - **Prefer 2 or 3 circles.** Avoid 4+ (unreadable — use a matrix instead).
 - Circle stroke: 1px hairline, color per-set (ink, muted, soft).
-- Circle fill: very low-opacity tint — `rgba(11,13,11,0.04)` for ink set, `rgba(82,83,78,0.05)` for muted. Tints compound naturally in overlap regions.
+- Circle fill: very low-opacity tint — `rgba(45,49,66,0.04)` for ink set, `rgba(79,93,117,0.05)` for muted. Tints compound naturally in overlap regions.
 - Radii: equal when sets are comparable in size; proportional when sets are meaningfully different. Don't fake equal sizes for aesthetics.
 - **Set labels** placed outside the circle, NEVER crossing the stroke. Geist 12–14px 600 for the set name, optional Geist Mono 9px sublabel.
 - **Intersection labels** placed inside the overlap region, Geist 12px 600, centered. For small overlaps, use a leader line to a label in clear space.
-- **Coral accent** on the ONE focal intersection — the "sweet spot". Either coral label stroke OR clipPath-bounded coral fill tint (`rgba(247,89,31,0.10)`).
+- **Coral accent** on the ONE focal intersection — the "sweet spot". Either coral label stroke OR clipPath-bounded coral fill tint (`rgba(235,108,54,0.10)`).
 - Circle centers and radii divisible by 4.
 
 ## Anti-patterns