FORGE-612 Upgrade updater-scripts demo to BrXM v17

[joeyliechty]

What

Upgrades the demo/ project from BrXM 16.3.1 to BrXM 17.0.0, including:

• Parent BOM bumped to hippo-cms7-enterprise-release:17.0.0 in demo/pom.xml and demo/src/pom.xml
• v17 bootstrap auto-export: new platform updater scripts (SetHasFoldersProperty, StdModifyPropertyCheck, VersionsCleaner), content migrations, and removal of deprecated workspace pages

Why

Resolves FORGE-612 — part of the broader BrXM v17 upgrade effort tracked in FORGE-582.

BrXM v17 introduces JDK 21 and Spring Boot 4. The updater-scripts repo contains no library code; only the demo project required updating.

How to test

1. Ensure JDK 21 is active
2. cd demo && mvn clean verify -DskipTests — confirm BUILD SUCCESS
3. mvn -Pcargo.run — confirm CMS starts at http://localhost:8080/cms with no SEVERE deploy errors
4. Log in as admin/admin — confirm dashboard loads
5. Navigate to Admin → Content Reports → Updater Editor — confirm Groovy updater console accessible

Checklist

• Build passing with Java 21 (mvn clean verify -DskipTests)
• Demo starts cleanly on BrXM 17.0.0 (Tomcat, CMS, site, essentials contexts all deploy)
• No breaking API changes (scripts are plain YAML/Groovy, no Java source)
• Manually verified on localhost
• support/16.x maintenance branch created from previous main tip

🤖 Implemented with Claude Code