allow "auto" for named local lambdas and iterator types via claude.md

.claude/CLAUDE.md

@@ -31,7 +31,14 @@ keep the citation accurate.
 ## Coding Guidelines
 
 * avoid duplicate code
-* do not use the "auto" keyword
+* do not use the "auto" keyword, with two exceptions:
+  * **named local lambdas** — a lambda's type is unnameable, and `std::function`
+    is not an acceptable substitute in per-tick code because it adds a heap
+    allocation and an indirect call
+  * **iterator types** — `auto it = m_buildings.find(id)` is allowed where
+    spelling the iterator out adds length without adding information
+  * everywhere else the type is written out; in particular `auto` is not used
+    for plain values, return values, or range-for element types
 * use Qt utility data types (like QPoint, QVector3D, QString, etc.)
 * wrap strings that appear in the UI with Qt's "tr()"
 * use the EventManager/EventHandler instead of defining own signals and slots