infra for deferred type variable

[lipingtababa]

Proposal Goal Enable variables to remain untyped until first use

Note You should investigate all the possibility before u make decisions. for exaple, you can use go module to read gogen code if needed

Scope Add deferred type tracking in cl/compile.go (symbol table extension) Implement placeholder type for untyped variables (types.Typ[types.UntypedNil] variant) Create deferred resolution queue mechanism No syntax changes - focus on internal infrastructure Deliverables New deferredVar structure to track unresolved variables Type resolution deferral mechanism in blockCtx Test cases in cl/_testgop/ for simple deferred inference scenarios Example Test Case x := 100 // deferred x + 200 // resolves to int Related Parent issue: xgo#2441 (Untyped Literal Extension) Part of Phase 1: Foundation - Deferred Type Inference Notes This is the foundational step that enables all subsequent steps in the untyped literal extension feature. It focuses on the internal infrastructure without any syntax changes.