Verbatim relocation of the 13-method protocol cluster (protocol decl
registration, param-protocol instantiation, thunk creation, vtable
globals, protocol-value construction, dispatch emission, impl lookup)
into src/ir/lower/protocol.zig. 13 fn aliases on Lowering keep all call
sites unchanged.
Two pub nested types travelled with the run (ProjectionPosition,
PackProjection) and are re-exposed via Lowering type aliases; they are
pack-domain types and may relocate to lower/pack.zig in B7.2.
Method pub-flips: allocViaContext, callForeign, genericInstanceMethod,
monomorphizeFunction.
Gate: zig build OK; zig build test 426/426; run_examples 541/0; zero
expected/ snapshot churn.
Verbatim relocation of the 23-method nominal-type cluster (struct/enum/
union/error-set registration, anon-type qualification, nominal-id
stamping, shadow-slot reservation, named-type interning, generic struct
templates + alias registration) plus the nested ShadowTypeDecl union
into src/ir/lower/nominal.zig. 23 aliases on Lowering keep all call
sites unchanged.
Method pub-flip: instantiateGenericStruct. nominal.zig reaches
VisibleStructAuthor and structDeclOfRaw (both relocated to decl.zig in
B4.1) via Lowering-namespace alias consts.
Gate: zig build OK; zig build test 426/426; run_examples 541/0; zero
expected/ snapshot churn.
Verbatim relocation of the 53-method error cluster (error typing,
raise/failable, try/catch/or, inferred-set convergence, trace runtime
hooks) out of the Lowering struct into src/ir/lower/error.zig as free
functions taking *Lowering. Each gets a pub-const alias on Lowering, so
every call site compiles unchanged (decl-alias method resolution).
Pub-flips (callees now referenced cross-file): lowerExpr, coerceToType,
freshBlock, freshBlockWithParams, emitErrorCleanup,
currentBlockHasTerminator, lowerBlock, lowerBlockValue.
Gate: zig build OK; zig build test 426/426; run_examples 541/0; zero
expected/ snapshot churn.
