docs: correct the Renovate claim in ROADMAP and drop a dead planning path

ROADMAP.md

@@ -27,8 +27,9 @@ particular:
   `quality-fuzz-monthly.yml`, `quality-soak-weekly.yml`
   (`benchmarks/cmd/{mockdocker,loadgen}` + `scripts/soak.sh`), and
   `quality-bench-monthly.yml`.
-- **Reproducible base images.** `Dockerfile` and `Dockerfile.release` pin
-  every base image by digest, with Dependabot tracking the `docker` ecosystem.
+- **Reproducible base images.** `Dockerfile`, `Dockerfile.armv7`,
+  `Dockerfile.dev`, `Dockerfile.release`, and `.clusterfuzzlite/Dockerfile`
+  pin every base image by digest, and Renovate keeps the digests current.
 - **Controller-owned watcher/update execution.** Portwing marks the Docker
   watcher as `transport=docker-api`, `execution=controller`, and
   `events=portwing`; Drydock runs its native watcher and update trigger through

scripts/ci/mutation-survivors-record.sh

@@ -36,10 +36,10 @@
 # sha256 over the whitespace-trimmed source lines l-2..l+2 (5 lines, each
 # followed by \x1f, missing lines padded with an empty string), and `o` is
 # the 0-based ordinal among mutants sharing (f, m, a) within the same source,
-# ordered by (line, column). See .planning/pw-2.5-survivor-payload-spec.md
-# for the measurement behind this choice: bare file+type+line collides 66 of
-# 335 times on this repo's real churn, and the 5-line window plus ordinal
-# resolves all but 3 genuine code changes.
+# ordered by (line, column). A hash of the mutated line alone is ambiguous
+# wherever a file repeats that line, and a line number moves with every edit
+# above it. The 5-line window survives unrelated edits elsewhere in the file,
+# and the ordinal separates mutants whose windows are still identical.
 #
 # Every {f,m,s,l,c} field below is sourced from a downloaded artifact: a
 # report the gremlins/mutation-advisory jobs produced by running mutated Go