docs(performance): single-source the gate composition

Three documents carried hand-maintained copies of the
verify-performance composition, and two had already drifted from the
recipes. ci-policy.md is now the one prose description (preflight.md
points there; the justfile stays the executable source of truth).
validation-summary.md — an unreferenced work-item summary whose gate
list was the stalest copy — and incremental-fastest-delta.md — by its
own header a point-in-time projection of the authoritative FPE-GAP
catalog that loses to it on every disagreement — are removed; the
README index names the catalog as the single delta ledger.

Author: johannhartmann

docs/performance/README.md

@@ -14,10 +14,9 @@ fixtures, and performance gate contracts.
   behavior.
 - [Known gaps](known-gaps.md): performance gaps that remain intentionally open.
 - [Fastest-engine known gaps](fastest-engine-known-gaps.md): the `FPE-GAP-*`
-  catalog of remaining fastest-engine deltas and their closure requirements.
-- [Incremental fastest-engine delta guard](incremental-fastest-delta.md):
-  current-`main` present/partial/report-only/absent classification and the
-  smallest remaining deltas, to stop reimplementation of existing features.
+  catalog of remaining fastest-engine deltas and their closure requirements —
+  the single authoritative delta ledger (point-in-time projections of it are
+  not committed; they drift).
 
 ## Optimization Areas
 

docs/performance/incremental-fastest-delta.md

@@ -31,27 +31,10 @@ Use the aggregate performance gate for performance-related changes:
 nix develop -c just verify-performance
 ```
 
-The gate includes:
-
-- `performance-tests`
-- `performance-regression` (includes the `perf-flag-matrix` A/B matrix)
-- `cache-roundtrip`
-- `optimizer-diff`
-- `quickening-smoke`
-- `inline-cache-smoke`
-- `jit-smoke`
-- `safety-audit-smoke`
-- `benchmark-smoke`
-- `framework-smoke`
-
-The release-profile and report gates run as `verify-performance-extended`
-(its own job in the CI gate matrix):
-
-- `release-benchmark-smoke`
-- `callgrind-smoke`
-- `hotpath-inventory`
-- `fastest-hotpath-report`
-- `perf-report`
+The gate composition (and the split into `verify-performance` and
+`verify-performance-extended`) is documented once, in
+[`ci-policy.md`](ci-policy.md); the `justfile` recipes are the executable
+source of truth.
 
 Long benchmark suites remain opt-in and are not default pull-request gates: