refactor: split optimizer/verifier/parser modules (mainline); add runner trace/directives; add LLVM terminator/select scaffolds; extract AST Span; update CURRENT_TASK with remaining plan

src/backend/llvm/compiler/codegen/instructions/select.rs

@@ -0,0 +1,16 @@
+/*!
+ * Select & Condition helpers (scaffolding)
+ *
+ * Placeholder for condition normalization / short-circuit pre-processing
+ * to keep `function.rs` focused on structure. Implementations will be
+ * added incrementally; for now, this module is documentation-only.
+ */
+
+use crate::mir::{function::MirFunction, ValueId};
+
+/// Normalize a branch condition if needed (scaffolding).
+/// Currently returns the input unchanged; provides a single place
+/// to adjust semantics later (e.g., truthy rules, short-circuit pre-pass).
+pub(crate) fn normalize_branch_condition(_func: &MirFunction, cond: &ValueId) -> ValueId {
+    *cond
+}