fix(release): replace \s with [[:space:]] in bump sed (BSD compat)

Critical: macOS BSD sed does not support \s character class.
The two substitutions in the version-bump step silently no-oped, the
grep fail-fast guard caught it (no remote damage), but release.sh
couldn't complete. Using POSIX [[:space:]] works on both BSD and GNU sed.

Also: extend test_git_archive_excludes_dev_files to cover .phpunit.result.cache,
.beads/, .claude/, dist/, .DS_Store — the test now fully enforces .gitattributes
export-ignore invariant.

tests/ZipArchiveBuildTest.php

@@ -52,7 +52,7 @@ final class ZipArchiveBuildTest extends Cf7stgTestCase
         $entries = self::listZip($zip);
         $joined = implode("\n", $entries);
 
-        foreach (['tests/', 'docs/', 'composer.json', 'composer.lock', 'phpunit.xml', 'release.sh', '.gitattributes', '.gitignore', 'CLAUDE.md', 'AGENTS.md'] as $devPath) {
+        foreach (['tests/', 'docs/', 'composer.json', 'composer.lock', 'phpunit.xml', 'release.sh', '.gitattributes', '.gitignore', 'CLAUDE.md', 'AGENTS.md', '.phpunit.result.cache', '.beads/', '.claude/', 'dist/', '.DS_Store'] as $devPath) {
             self::assertStringNotContainsString(
                 "cf7-spam-to-telegram/$devPath",
                 $joined,