Retitle sins to name the problem plainly

Titles are scanned in the gallery and recognized in a link, so they
should say what the sin is rather than pun about it. Retitles the three
published sins and the backlog's working titles, and records the rule in
CLAUDE.md: the title names the problem, the poke carries the voice.

Filenames are untouched, so existing URLs still resolve.

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

CLAUDE.md

@@ -14,6 +14,11 @@ Each sin page follows one shape: **poke → proof → why → the fix → receip
 
 ## Voice & content conventions
 
+- **The title names the problem plainly; the poke carries the voice.** A title
+  is a label someone scans in the gallery and recognizes in a link — write
+  "Truncated Y-Axis on a Bar Chart," not "The Truncated Temptation." Use the
+  field's standard term for the sin where one exists. Save the wit for the poke;
+  that's what it's for.
 - **The poke names the general sin, never the sample's specifics.** A visitor
   didn't "start the axis at 90" — they mis-set the baseline. Write
   "Your bars don't start at zero…", not the numbers from our example data.