build: bump Gentoo and Void versions in release-version

Move version bumping into scripts/bump-version.sh, rename the ebuild per release, reset the Void checksum, and add make pkg-checksums to fill it after the release.

scripts/bump-version.sh

@@ -0,0 +1,23 @@
+#!/bin/sh
+# Usage: scripts/bump-version.sh X.Y.Z
+# Updates the version in source and every package definition.
+# Run from the repo root. Void checksum is reset: fill it with
+# scripts/update-checksums.sh once the release tarball exists.
+set -eu
+
+VER="${1:?usage: $0 X.Y.Z}"
+EBUILD_DIR=pkg/gentoo/app-containers/unitdore
+
+sed -i "s/^var version = .*/var version = \"$VER\"/" cmd/root.go
+sed -i "s/^pkgver=.*/pkgver=$VER/" pkg/arch/PKGBUILD
+sed -i "s/^Version:.*/Version:        $VER/" pkg/centos/unitdore.spec
+
+# Gentoo: the version lives in the ebuild file name
+OLD_EBUILD=$(ls "$EBUILD_DIR"/unitdore-*.ebuild | head -n1)
+NEW_EBUILD="$EBUILD_DIR/unitdore-$VER.ebuild"
+[ "$OLD_EBUILD" = "$NEW_EBUILD" ] || git mv "$OLD_EBUILD" "$NEW_EBUILD"
+
+# Void: version bump invalidates the checksum
+sed -i -e "s/^version=.*/version=$VER/" \
+       -e "s/^revision=.*/revision=1/" \
+       -e "s/^checksum=.*/checksum=UPDATE_AFTER_RELEASE/" pkg/void/srcpkgs/unitdore/template

scripts/update-checksums.sh

@@ -0,0 +1,13 @@
+#!/bin/sh
+# Usage: scripts/update-checksums.sh
+# Fills the Void template checksum from the published release source tarball.
+# Run from the repo root after the release workflow has finished.
+set -eu
+
+T=pkg/void/srcpkgs/unitdore/template
+VER=$(sed -n 's/^version=//p' "$T")
+URL="https://git.warky.dev/wdevs/unitdore/releases/download/v$VER/unitdore-v$VER-source.tar.gz"
+
+SUM=$(curl -fsSL "$URL" | sha256sum | cut -d' ' -f1)
+sed -i "s/^checksum=.*/checksum=$SUM/" "$T"
+echo "void checksum for v$VER: $SUM"