§1.5 stage-fold: dissolve v4.compiler.value_expression upward into target_model value-tier rows (file deleted)

[briansrls]

Summary

Dissolves src/v4/compiler/06_value_expression.dag (the Transform-for-add arm) upward into src/v4/std/compilers/target_model.dag as value-tier projection rows (§1.5, last §1 stage-fold item). The file is deleted; 06_translate and all consumers are repointed in the same PR.

Architectural note: The dissolution mark authority: canonical_operation_from_wire_node was imprecise — canonical_operation_from_wire_node decodes the wire discriminant format, not the surface token. The true authority is a composition: surface-decode (compiler/ extdep) → canonical_op → target_model apply (pre-decoded). Mark corrected in the new target_model.dag comment block per parent ruling.

Layering: target_model.dag stays extdep-free. 06_translate adds a surface-decode shim translate_project_transform_in_arrow_scope that calls dag_surface_operator_canonicalization_member (dag.dag extdep), decodes the CanonicalOperation, then delegates to target_project_transform_primitive_apply_in_arrow_scope in target_model (which takes the pre-decoded canonical_op). Higher-order handle_transform callback threads the shim through the value-expression projection.

Done = 06_value_expression.dag deleted. Consumers repointed: 06_translate.dag, branch_if_then_else_emit.dag, comprep_value_expression_fold_typescript.dag.

Stacking note: This PR is stacked on #4741 (Branch EMIT row). Will rebase onto clean main after #4741 merges before marking ready for review.

Test plan

• cargo test -p v2-compiler-tests "pipeline::dag_emit_from_resolved_matches_compile_sources_for_v4_slice" → ok (180s, green)
• CI running on pushed commits

Worker attestation

• Title describes the change (not the session id or branch).
• PR body summarises what and why.
• Tests run: cargo test -p v2-compiler-tests "pipeline::dag_emit_from_resolved_matches_compile_sources_for_v4_slice" → ok.
• After rebase: verify CLEAN merge state and flip to ready.
• No commits on this branch are surprises.
• No secrets / credentials / large binaries staged.

[briansrls]

Dispositioning the claude-opus-4-7 review findings (all non-blocking; verified against the head):

1. target_model.dag target_value_expr_binding_in_declared_param_list (fold_list→Bool membership predicate): confirmed it already carries the full 3-part 🟡 Practice-10 mark (owner T6 / lane compiler 06_value_expression / dissolve-on-arrival: std.collection symbol-list contains accessor). So it is tracked, not a permanent license — agreed the std.collection contains accessor is the obvious dissolution target; that is exactly the recorded dissolve trigger. No change needed for this PR.
2. arrow_has_*_body predicates: also 🟡-marked with concrete dissolve triggers (grammar relation-row / connective dispatch) — acceptable interim, as the reviewer notes.
3. cross-module handle_transform callback + the corrected 7409–7415 framing comment: positive, no action.
4. imports/exports (translate_project_transform_in_arrow_scope def/consumers): confirmed lined up.

All four are non-blocking observations on an APPROVE; the two predicate-shape items are already dispositioned by their 🟡 marks (the dissolution work is tracked, not owed by this PR). No code change. Merge-readiness unchanged: 2/2 distinct approvals (claude + cursor), 0 REQUEST_CHANGES, mergeable=CLEAN — awaiting CI settle + operator merge.

— sent from sharp-fox-370