Records build and their fields read, end-to-end under `ckc test`.
Codegen/Floor-IR only (front-end already parses/resolves records).

Layout per arenas.md static frame layout: no header, no GC, no per-object
free. Offsets = running byte sum in field order; size = sum. Int field =
i64 (8B); String field = (ptr,len) pair (16B, two words) -- correctly
shifts later fields' offsets. 8-byte aligned.

New Floor IR nodes Record{fields} + FieldAccess{receiver,field} (lower.rs);
new codegen/record.rs: emit_record_addr constructs into a Cranelift stack
slot via a base pointer, emit_field_values projects at the field offset.
Reached through a base pointer (stack_addr today) so the same layout is
arena-placeable later by swapping the base origin -- nothing else is
stack-specific. Wired through assert.rs + concat.rs emit_arg so a projected
field is a valid Assert::equal operand and effect-op argument.

Gate: tests/corpus/record_fields + Docker-gated record_fields_run --
point_projects_fields (Int offsets 0/8) and string_field_shifts_offsets
(trailing Int read past a 16B String field) both pass. Front-end clean
(no trap.md), in the RUNTIME_TESTED allow-list with justification.

Out (cited): let/if/match (R2), data/variants (P2.3), collections (P2.4),
String == (P2.5), mocked effects (P2.6), record with-update, value-
returning fns, destructuring.

Gates: fmt clean; clippy 0/0; cargo test --workspace 914 passed;
greeter/helloWorld unchanged; record fixture green. record.rs cka-clean.

@@ -285,0 +405,4 @@
+
+/// Print one `trap.md` block: a `### <File>` heading and a ```` ```trap ```` fence
+/// holding the lowered `E####: line, col` lines (empty fence = clean).
+fn print_trap_block(file_name: &str, traps: &[ck_cktest::TrapLine]) {

@@ -0,0 +120,4 @@
+        .arg("--stdlib")
+        .arg(&stdlib)
+        .status()
+        .expect("spawn the `ckc` binary")

@@ -0,0 +190,4 @@
+    let slot = fb.create_sized_stack_slot(data);
+    let base = fb.ins().stack_addr(inputs.pointer, slot, word_offset(0));
+    for field in &plan {
+        let mut values = Vec::new();