fix(release-script): install render-pptx before regenerating the showcase

[DemchaAV]

What happened

The 2.1.0 cut aborted at Step 4:

[ERROR] Could not resolve dependencies for project io.github.demchaav:graph-compose-examples:jar:2.1.0
[ERROR] dependency: io.github.demchaav:graph-compose-render-pptx:jar:2.1.0 (compile)
[ERROR] 	Could not find artifact … in central
Exception: ShowcaseSync failed (exit 1)

No commit and no tag were created — but by that point Step 1 had already rewritten all 13 poms, the root and eight module READMEs, web/index.html, the release-smoke defaults, and Step 2 had dated the changelog. 29 modified files to unwind by hand, at the exact moment a release is least forgiving.

Why

cut-release.ps1:518 installs the examples module's siblings from a literal list so that ShowcaseSync can resolve them at the just-bumped version, which exists in no repository yet:

$exampleSnapshotSiblings = @('render-pdf/pom.xml', 'wrapper/pom.xml', 'render-docx/pom.xml',
                             'templates/pom.xml', 'testing/pom.xml')

The list predates render-pptx. examples/pom.xml took a compile dependency on it for the PPTX twin examples, and nothing connected the two. The failure cannot surface before a cut, because it needs a version that only exists mid-cut.

render-pptx is inserted after render-pdf, which it depends on at compile scope.

The guard

A literal list that must track another file will drift again — this is the second release-script list to do so. ReleaseScriptInstallListGuardTest derives the required set from examples/pom.xml and fails the build when the script does not cover it.

Two deliberate scoping decisions, both from what the pom actually says:

• Only ${graphcompose.version} dependencies count. graph-compose-fonts and graph-compose-emoji sit on independent release lines (${graphcompose.fonts.version} / ${graphcompose.emoji.version}) and resolve from Central, so a cut never builds them. An earlier draft matched every graph-compose-* artifactId and demanded those two plus the <parent> coordinate — wrong on all three.
• The reverse direction is not asserted. The list legitimately carries render-pdf, which the examples reach transitively through the graph-compose wrapper and which is bumped all the same. A subset assertion would have flagged it.

Verification

ReleaseScriptInstallListGuardTest passes with the fix; reverting just the list entry turns it red, so it is driving the behaviour rather than restating it.

Dry-run across all three modes — the v1.6.5 lesson that a release step working in the default mode is not enough:

Mode	Exceptions	Installs render-pptx
-Version 2.1.0 -DryRun	0	yes
-Version 2.1.0 -DryRun -SkipShowcase	0	no, as intended — the mode skips showcase entirely
-PostReleaseOnly -DryRun	0	yes