chore(debug): try --disable-split-sections to avoid GHC crash

Crash invariantly at position 287,686,318 bytes happens after all 477 modules
compile. Hypothesis: split-sections expands ELF section count, triggering
GHC's internal ELF merger/linker to fail when reading the combined object.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

flake.nix

@@ -124,7 +124,7 @@
                                            configureFlags = (old.configureFlags or []) ++ [
                                                "--ghc-option=-O0"
                                                "--ghc-option=-fomit-interface-pragmas"
-                                               "--ghc-option=-ddump-if-trace"
+                                               "--disable-split-sections"
                                            ];
                                            postUnpack = (old.postUnpack or "") + ''
                                                _actual="$sourceRoot/build/Generated/ActualTypes.hs"