Merge origin/main into local main. Keep both on the three conflicts.

v0-neuron is in this history. origin/main architecture and soul are in too. Sort later.

.gitignore

@@ -37,3 +37,18 @@ runs/rung1/universe.db*
 evolve/
 garden/
 /neuron
+# ---- keep both, sort later: local main (v0) then origin/main ----
+# Compiled binaries
+dist/neuron
+dist/neuron.backup-*
+dist/*.backup-*
+
+# Build artifacts
+*.o
+*.a
+
+# Regenerate scratch dir (build artifact — never commit)
+dist-fresh/
+
+# macOS
+.DS_Store