feat: support no-evals in perf changelog entries

[cquil11]

Summary

Add opt-in no-evals: true to perf-changelog.yaml entries so PR sweeps can run throughput-only validation through the normal full-sweep-enabled workflow. This is needed by #2931 to validate Prometheus cache-source attribution without rerunning model-quality evals.

• Defaults remain unchanged; benchmark duration, collection, and artifacts are unchanged.
• Skip all four eval families for the opted-out entry. Other entries can still request evals, including for overlapping configurations.
• Reject conflicting entry-level eval selectors and PR-wide eval modifiers.
• Preserve the flag in changelog metadata; document that these runs do not provide model-evaluation evidence.

Validation

uv run --no-project --with pytest --with pydantic --with pyyaml --python 3.12 pytest utils/test_process_changelog.py utils/matrix_logic/test_validation.py utils/changelog_gate_tests/ -q

311 passed. Tests exercise throughput preservation, default behavior, entry isolation, metadata, and conflicting options. No GPU recipe changes in this PR. Prepared with AI assistance.

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Note

Medium Risk
Changes PR sweep matrix composition and validation gates; misconfiguration could skip evals unintentionally, though the flag is opt-in and guarded by explicit conflict checks and tests.

Overview
Adds no-evals: true on perf-changelog.yaml entries so a normal full-sweep-enabled PR can run throughput-only for those entries without PR-wide evals-only / --no-evals CLI tricks.

process_changelog still generates benchmark rows with the existing --no-evals generator path, then skips all eval matrix generation for opted-out entries (same early-exit pattern as append-only). no-evals is per-entry: another changelog line can still schedule evals for overlapping configs. The flag is validated against conflicting entry fields (evals-only, all-evals, eval-min-prefill-ep) and against PR modifiers --all-evals / --evals-only.

ChangelogEntry in infx/matrix/validation.py defines the new field (default false). English and Chinese eval procedure docs describe throughput-only sweeps and that these runs are not model-evaluation evidence. Tests cover throughput preservation, metadata, entry isolation, and rejection of conflicting options.

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[claude]

Nothing blocking. The comments below are optional suggestions. There is no need to push a fix for them before merging.

[claude]

🟡 (optional) The Chinese translation drops the "combined with no-evals" qualifier, so it reads as an absolute ban on using all-evals/evals-only/eval-min-prefill-ep together (or the two PR modifiers together) — which contradicts actual validator behavior (an entry may freely combine evals-only with eval-min-prefill-ep, or all-evals is just mutually exclusive with evals-only at CLI level, absent no-evals). Chinese-only readers get a false validation rule not present in the English page or the code. Fix: retranslate to explicitly tie the prohibition to no-evals, e.g. "与 no-evals 同时使用 all-evals/evals-only/eval-min-prefill-ep，或在 PR 上同时使用 no-evals 与任一 eval PR modifier，都会被拒绝", matching validation.py's validate_append_only_mode and process_changelog.py's no_evals/all_evals/evals_only check.

Extended reasoning...

English (docs/eval-agentx-procedures.md:20-21): "Combining no-evals with all-evals, evals-only, or eval-min-prefill-ep on the entry, or with either eval PR modifier, is rejected" — the ban is conditioned on no-evals, matching infx/matrix/validation.py's model_validator (raises only when self.no_evals is True) and process_changelog.py's main() (raises only when any entry.no_evals and args.all_evals/evals_only). The zh page (lines 18-20) renders this as "条目中不能同时使用 all-evals、evals-only 或 eval-min-prefill-ep，PR 也不能同时使用两个 eval modifier 中的任意一个" — omitting the no-evals connector entirely, so it states an entry can never combine those three fields, and a PR can never use both eval modifiers, neither of which the code actually enforces outside the no-evals case. A Chinese-reading operator following only this page would believe legal configurations (e.g. evals-only + eval-min-prefill-ep) are forbidden.

Verification: nit (docs-only, no runtime break, but introduces false content the base lacks). English docs/eval-agentx-procedures.md:18-20 conditions the rejection on no-evals: "Combining no-evals with all-evals, evals-only, or eval-min-prefill-ep on the entry, or with either eval PR modifier, is rejected." This mirrors infx/matrix/validation.py validate_append_only_mode, which raises ONLY when…