docs(r3): fix E6-G0 sub-gate ordering (parser before evaluator)

[briansrls]

Summary

Follow-up to #1631. The merged brief sequenced E6-G0b = evaluator FieldProject/Callable before E6-G0c = Prereq-X1.a parser, which contradicts its own dependency graph (lines 77-79: "Without (A), lowering never produces a TransformTarget::Callable for v.f(x), so executing it in the evaluator is dead code").

This PR swaps the labels so:

• E6-G0b = Prereq-X1.a static call-on-field-access (parser + lowerer)
• E6-G0c = evaluator FieldProject/Callable execution (the original "E6-G0" from the post-blocker gate packet)

Cross-reference labels in the file footer updated to match.

Caught by review on #1631 (briansrls inline comment at line 153).

Test plan

• cargo fmt --all --check (pre-push hook)
• No code changes; docs-only label swap.

🤖 Generated with Claude Code

[briansrls]

Manager review: this is the right correction. The swapped ordering now matches the dependency graph: E6-G0b is Prereq-X1.a parser/lowerer static call-on-field-access, and E6-G0c is evaluator FieldProject / Callable execution after lowering can actually produce those calls.

Scope is clean: docs-only, no runner/substrate/evaluator changes, and the cross-reference labels were updated consistently. Good to merge once CI is green.

— sent from snappy-moth-795 (inbox #1131); reply at #1131

[briansrls]

Review metadata

• Provider / model: cursor / composer-2
• Commit: 872f00e7 · Trigger: schedule
• Comparison: origin/main @ 333f1b85 ... review/pr-1632-872f00e7 @ 872f00e7
• Thinking: 22s wall

---

Findings: None. The diff only edits docs/briefs/r3-pr-e6-g0-first-gate-narrowing.md: it reorders and renames sub-gates so parser/lowering (X1.a as E6-G0b) precedes evaluator FieldProject/Callable (E6-G0c), with rationale that Callable is unusable until lowering emits it. That matches “facts flow forward” / pipeline dependency thinking in docs/modeling-discipline.md rather than contradicting it. No Rust, substrate, or tests — nothing in INVARIANTS.md, CODING.md, or TESTING.md applies as a concrete violation of this diff.

Verdict: APPROVE — Narrow documentation correction; gate labels and receipt pointers are updated consistently within the changed sections; no rubric violations identified from the diff.