Add real-world specimens and cross-links between sins

Two new levers on a sin page. `wild[]` renders credited, linked
specimens between the explanation and the citations — first the
argument, then proof people actually publish this, then the sources.
`related[]` cross-links neighbouring sins and is resolved at build, so a
typo fails the build instead of shipping a dead link.

Both arrive with the first specimen: a Hungarian primary graphic whose
three slices read 38/22/19 — 79% — drawn as a full circle, so every
share is inflated by about 1.27x. Measured off the image, the 38% slice
occupies 173.6 degrees, or 48.3% of the pie.

Our published pie sin is about too many slices, so it didn't cover this;
"Pie Slices That Don't Sum to the Whole" is a new severity-5 page whose
before/after is two pies differing only in whether the remainder is
present. That sin is an omission, so `compareNote` replaces the standard
"same numbers, both charts" line.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ULE5RRxdQE1ebwefEd2eCM

CLAUDE.md

@@ -88,6 +88,14 @@ Each sin page follows one shape: **poke → proof → why → the fix → receip
    `badChart`/`fixedChart` are the spec basenames (no `.json`). `citations[].key`
    must exist in `src/lib/references.ts` (build throws otherwise).
 3. New reference? Add it once to `src/lib/references.ts`, then cite its key.
+   Optional frontmatter worth knowing about:
+   - `wild[]` — real specimens of the sin, rendered above the citations. Always
+     `credit` the original and link `sourceUrl` where we found it. A chart that
+     commits two sins goes on both pages with a different `note` on each.
+   - `related[]` — slugs of neighbouring sins; validated at build, so a typo or
+     a renamed slug fails the build rather than shipping a dead link.
+   - `compareNote` — overrides "Same numbers, both charts," which is wrong on a
+     sin whose whole point is an omission.
 4. `npm run dev` and check. The OG card for the sin is generated automatically.
 
 ## Design & rendering