docs(perf): measure the 0.12.0 candidate against 0.11.0

changes/unreleased/perf-0.12.0-record.added.md

@@ -0,0 +1 @@
+- `docs/project/performance-release-0.12.0-vs-0.11.0.md` records the release-gate measurement of 0.12.0 against 0.11.0 in three columns — 0.11.0 as released (go1.25.11), 0.11.0 rebuilt with go1.27.3, and the candidate, first before and then after its performance fixes — so that the toolchain change and the source changes are told apart: every benchmark on each, `benchstat` over six rounds, whole-binary timings on generated and real models, the stress constellation, the export element-ID rows #1699 fixed, and the merge each regression traces to, with the fix pull request each motivated listed as it lands.

docs/internals/performance.md

@@ -5,7 +5,7 @@ say about where the remaining cost is. Figures below were taken on an
 `Intel Xeon Platinum 8559C`, Go 1.25, `GOMAXPROCS=8`; treat them as
 ratios rather than absolutes. Each release is measured against the one before it
 in a record under `docs/project/`; the latest is
-[release 0.11.0 against release 0.10.1](../project/performance-release-0.11.0-vs-0.10.1.md); the [0.10.1 against 0.10.0](../project/performance-release-0.10.1-vs-0.10.0.md) record precedes it and the earlier records are in the [archive](../project/archive/README.md).
+[release 0.12.0 against release 0.11.0](../project/performance-release-0.12.0-vs-0.11.0.md); the [0.11.0 against 0.10.1](../project/performance-release-0.11.0-vs-0.10.1.md) and [0.10.1 against 0.10.0](../project/performance-release-0.10.1-vs-0.10.0.md) records precede it and the earlier records are in the [archive](../project/archive/README.md).
 How far one realistic model scales — a satellite constellation with every
 spacecraft modeled to its components, from 2 to 12 800 satellites — and where
 validation, satisfaction checking and editing each stop being practical is in

docs/project/README.md

@@ -102,11 +102,12 @@ within these records and means nothing outside this repository.
 - **[StateMachines library](statemachines-library.md)** — pseudostates as bundled
   `SemanticMetadata`, so a state machine's `choice`, `junction` and history pseudostates
   spell standard, conforming SysML v2
-- **[Performance: 0.11.0 against 0.10.1](performance-release-0.11.0-vs-0.10.1.md)** — the release-gate
-  measurement of the release candidate against the release before it: every benchmark on both
-  revisions, the rows in doubt re-run interleaved, whole-binary scaling, and each confirmed regression
-  with the change responsible; the [0.10.1 against 0.10.0](performance-release-0.10.1-vs-0.10.0.md)
-  record precedes it, and the records of the earlier releases and the September 2026 census, execution
+- **[Performance: 0.12.0 against 0.11.0](performance-release-0.12.0-vs-0.11.0.md)** — the release-gate
+  measurement of the release candidate against the release before it, in three columns so the Go
+  toolchain change is told apart from the source changes: every benchmark on each, the rows in doubt
+  re-run interleaved, whole-binary scaling, and each confirmed regression with the change responsible;
+  the [0.11.0 against 0.10.1](performance-release-0.11.0-vs-0.10.1.md) and
+  [0.10.1 against 0.10.0](performance-release-0.10.1-vs-0.10.0.md) records precede it, and the records of the earlier releases and the September 2026 census, execution
   study and profile are in the [archive](archive/README.md)
 - **[Roadmap](roadmap.md)** — the known gaps, in the order they should be picked up
 - **[Nightly snapshots](nightly.md)** — the prerelease built from `develop` every night: where it