Release v0.4.2: confirm the date and bump the version

One commit, so the tree that gets built and checked is the tree that gets
tagged. Splitting the date from the version bump would leave the deb sanity
checks running against a tree that later changes, and open a delta in the
tagged-versus-validated assertion that step exists to close.

The date is confirmed at 2026-08-25 in all three files that carry it:
CHANGELOG.md's [0.4.2] heading and the Released line in both RELEASE-NOTES.md
and docs/releases/release-notes-v0.4.2.md. v0.4.0 shipped a wrong date in two
of those three because the step was scoped to one file, so the assertion here
greps the whole of docs/releases/ rather than only this release's files, and it
returns nothing. The two release-notes files are byte-identical again after the
edit, checked with cmp.

Version goes to 0.4.2, with Cargo.lock following via cargo update -w. build.rs
and src/version.rs are untouched.

The notes' "144 commits since v0.4.1" is deliberately left alone. It counts
substantive change and excludes the two release-preparation commits, so
git rev-list returns 146 and disagrees with it. That definition is recorded in
the release's surprises file so it is not later corrected by measurement.

CHANGELOG.md

@@ -7,13 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
-<!-- The 0.4.2 date below is provisional and is confirmed at the tag, together
-     with the same date in RELEASE-NOTES.md and in
-     docs/releases/release-notes-v0.4.2.md. All three carry it; a prior release
-     shipped a wrong date in two of the three because the confirm step was
-     scoped to one file. -->
-
-## [0.4.2] - 2026-08-24
+## [0.4.2] - 2026-08-25
 
 ### FMP/FSP sessions and rekey
 

Cargo.lock

@@ -1087,7 +1087,7 @@ checksum = "9844ddc3a6e533d62bba727eb6c28b5d360921d5175e9ff0f1e621a5c590a4d5"
 
 [[package]]
 name = "fips"
-version = "0.4.2-dev"
+version = "0.4.2"
 dependencies = [
  "arc-swap",
  "bech32",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "fips"
-version = "0.4.2-dev"
+version = "0.4.2"
 edition = "2024"
 description = "A distributed, decentralized network routing protocol for mesh nodes connecting over arbitrary transports"
 license = "MIT"

RELEASE-NOTES.md

@@ -1,7 +1,6 @@
 # FIPS v0.4.2
 
-**Released**: 2026-08-24 (provisional: the date is confirmed when the
-release is tagged)
+**Released**: 2026-08-25
 
 v0.4.2 is a maintenance release on the v0.4.x line, and the largest one
 this line has carried: 144 commits since v0.4.1. Most of it is security

docs/releases/release-notes-v0.4.2.md

@@ -1,7 +1,6 @@
 # FIPS v0.4.2
 
-**Released**: 2026-08-24 (provisional: the date is confirmed when the
-release is tagged)
+**Released**: 2026-08-25
 
 v0.4.2 is a maintenance release on the v0.4.x line, and the largest one
 this line has carried: 144 commits since v0.4.1. Most of it is security