refactor: enable oxc_ast's disable_old_builder feature

[Boshen]

Enables oxc_ast's disable_old_builder cargo feature — the endgame of the oxc#23043 AstBuilder redesign, ahead of oxc removing the old builder methods entirely. All construction call sites were already on the new per-type-constructor API, so this is the enforcement pass; it also stops compiling the deprecated 599 KB generated/ast_builder.rs.

The oxc umbrella crate has no passthrough for the feature, so it is enabled through a direct oxc_ast dependency carried by rolldown_ecmascript; cargo feature unification applies it to the copy the umbrella re-exports. The dep is cargo-shear-ignored — no code references oxc_ast:: paths directly, and without the ignore, CI autofix would remove the dep and silently disable the feature.

Changes forced by the feature:

• AstBuilder is no longer Copy/Clone, so AstFactory isn't either. The two by-value copy sites now reconstruct a handle (AstFactory::new(alloc) is a free wrapper over the arena reference) or borrow it.
• ConstantValue::to_expression and json_value_to_expression take &AstBuilder; the HmrAstBuilder::builder impls construct a fresh AstBuilder::new(allocator()) instead of deref-copying, leaving their call sites untouched.
• The top-level oxc::ast::{AstBuilder, NONE} re-exports are removed by the feature; imports now use oxc::ast::builder::{AstBuilder, NONE}.

Also updates internal-docs/ast-construction/implementation.md (migration completion note, corrected sample) and adds oxc_ast to the upgrade-oxc skill's version-bump lists so the pin moves in lockstep on future upgrades.

A cleaner follow-up on the oxc side would be an umbrella passthrough feature (disable_old_builder = ["oxc_ast/disable_old_builder"]), after which the direct dep here can be dropped.

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[codspeed-hq]

Merging this PR will not alter performance

✅ 7 untouched benchmarks
⏩ 10 skipped benchmarks¹

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_{Comparing enable-disable-old-builder (f8100a9) with main (2fd5c5c)}

Footnotes

1. 10 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[hyfdev]

Reviewed at f8100a991928fcac05a3f4704669b1447bb8d315.

The feature-only oxc_ast dependency correctly enables disable_old_builder through Cargo feature unification, and the import/ownership migration preserves the pinned Oxc 0.140 semantics. I verified the full diff and dependency graph, cargo check --workspace --all-features --all-targets --locked, the JSON AST tests, formatting, and cargo-shear.

The red Vite Test Ubuntu job is the same pre-existing source-map snapshot mismatch on the base commit. The branch is still behind main, so the normal update/merge-gate rerun remains. No blocking findings.

[overlookmotel]

We can clean this up further, shortening code. I'd also like to propose changes to AstFactory - I'll open an issue for that.

We intend to imminently remove the old AstBuilder from Oxc entirely, and with it remove the disable_old_builder Cargo feature - so that complication will go away shortly.

I'd recommend merging this, I'll open an issue to discuss the changes I have in mind for AstFactory, and I can work on it next week.

Not sure why Vite Test Ubuntu job is failing CI. I don't have the context to say if it's related to these changes, but I suspect not.

[overlookmotel]

Opened issue about proposed changes to AstFactory: #10328

[hyfdev]

Merge activity

• Jul 17, 2:55 AM UTC: The merge label 'graphite: merge-when-ready' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
• Jul 17, 2:55 AM UTC: hyfdev added this pull request to the Graphite merge queue.
• Jul 17, 3:01 AM UTC: Merged by the Graphite merge queue.