Consolidate required CI gate (#115)

docs/ci-runtime-evidence.md

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+# Required CI runtime evidence
+
+This record is populated from the consolidated `CI / required` Gitea job. A
+qualifying sample consists of one deliberate cold native/dependency cache run
+and four normal warm-cache runs on `aarch64-unknown-linux-gnu`. Each uploaded
+`required-gate.json` contains per-stage elapsed time, Rust host/target, separate
+compiled-Cargo, dependency-download, native, and tool cache hit state,
+available peak-memory evidence, and the Skia binary outcome.
+
+The compiled target key includes Rust 1.97.1, the ARM64 GNU target, every Cargo
+manifest, `Cargo.lock`, required feature/policy configuration, and native
+installer inputs. CI-driver-only changes reuse the newest generation through a
+same-filesystem hard-link migration; Cargo still validates every fingerprint.
+To invalidate compiled artifacts, change a keyed build input. A deliberate
+`cold_cache` dispatch removes registry archives/index data, Git database data,
+pinned audit tools, OpenJPEG, and Skia. It retains immutable extracted registry
+sources and the compiled target so the cold dependency/native measurement does
+not manufacture source-mtime rebuilds unrelated to cache correctness.
+
+The pre-consolidation Gitea baseline was 13 automatic workflows and 333 runs.
+Successful maxima included 22.9 minutes for the native workspace, 32.0 minutes
+for Skia, 66.6 minutes for artifact audit, and 86.0 minutes for the release
+matrix. Native code generation had a 13.2-minute median and 18.5-minute maximum;
+even this one concern could exceed the new complete-gate budget.
+
+| Run | Cache | Elapsed | Result | Evidence |
+| --- | --- | ---: | --- | --- |
+| [423](https://git.rfc1437.de/hugo/MetaCrate/actions/runs/391) | cold (compiled hit; dependency/native/tool miss) | 4:24 | success | [required-ci-evidence](https://git.rfc1437.de/hugo/MetaCrate/actions/runs/391/artifacts/required-ci-evidence) |
+| [424](https://git.rfc1437.de/hugo/MetaCrate/actions/runs/392) | warm | 3:56 | success | [required-ci-evidence](https://git.rfc1437.de/hugo/MetaCrate/actions/runs/392/artifacts/required-ci-evidence) |
+| [425](https://git.rfc1437.de/hugo/MetaCrate/actions/runs/393) | warm | 3:56 | success | [required-ci-evidence](https://git.rfc1437.de/hugo/MetaCrate/actions/runs/393/artifacts/required-ci-evidence) |
+| [426](https://git.rfc1437.de/hugo/MetaCrate/actions/runs/394) | warm | 3:55 | success | [required-ci-evidence](https://git.rfc1437.de/hugo/MetaCrate/actions/runs/394/artifacts/required-ci-evidence) |
+| [427](https://git.rfc1437.de/hugo/MetaCrate/actions/runs/395) | warm | 4:12 | success | [required-ci-evidence](https://git.rfc1437.de/hugo/MetaCrate/actions/runs/395/artifacts/required-ci-evidence) |
+
+The uploaded evidence reports the following internal gate timings. Warm values
+are the observed minimum and maximum across the four warm runs.
+
+| Stage | Cold seconds | Warm seconds |
+| --- | ---: | ---: |
+| static/generated/API | 119.200 | 118.291–119.204 |
+| reviewed reports | 0.000 | 0.000 |
+| Skia binary proof | 0.343 | 0.250–0.262 |
+| compile/test/features | 38.429 | 37.031–37.590 |
+| program/API smoke | 2.876 | 2.416–2.526 |
+| clippy/docs | 1.243 | 1.032–1.080 |
+| policy/evidence | 7.669 | 7.272–7.469 |
+| complete internal gate | 201.202 | 197.423–198.555 |
+
+All five consecutive runs used commit `05af8d5edf566fb79770990153d8561a98718ec4`
+on the ARM64 `ubuntu-latest` runner. The 4:24 maximum leaves 10:36 of headroom
+under the 15-minute job timeout. Branch protection for `main` enables status
+checks with `CI / required (push)` as its only required context; direct-push
+behavior is unchanged. Every evidence record reports `aarch64` with Rust
+host/target `aarch64-unknown-linux-gnu`; observed peak cgroup memory is
+264,696–264,712 KiB. Every Skia proof installed the pinned archive with SHA-256
+`dd127f458a5e67a79f3936a8aa19f822fe90a1d6a11b50b5f84df2b0519d909c`
+and records that no source build started.