Reframe the reference list; cite far more widely

"Canon" was leaking onto the public site — a nav item, a footer block, a
page title, a set of CSS class names. It was also driving content
decisions it had no business driving: the backlog was ordered around
which references were still unused, which is curation dressed up as
planning.

The page is now /references/, the list is documented as a bibliography
to grow rather than a canon to curate, and the backlog says plainly that
a sin earns a slot by being worth a page — sources are found to support
it, never the reverse.

Adds six sources (Cairo's Truthful Art, Few's Show Me the Numbers, the
Economist's audit of its own charts, Kosara's eagereyes, WTF
Visualizations, Datawrapper's dual-axis piece) and roughly doubles the
citations on the five published sins, to 5-7 each. Two of the new notes
point at sources that complicate our own position rather than back it.

The Economist essay ships without a URL rather than a guessed one.

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

src/content/sins/too-many-pie-slices.md

@@ -17,6 +17,12 @@ citations:
     note: "Kaiser Fung’s running #onelesspie campaign exists for precisely this chart."
   - key: datatoviz
     note: "Pie charts are the first entry in its catalogue of caveats."
+  - key: wilke
+    note: "His chapter on proportions puts the same data in a pie, a stacked bar and side-by-side bars, so you can see what each one costs you."
+  - key: eagereyes
+    note: "Kosara has actually run the experiments, and complicates the blanket condemnation — read him before swearing off pies entirely."
+  - key: showmenumbers
+    note: "Few’s full design manual, for when the short broadside isn’t enough to win the argument."
 ---
 
 ## The sin