Add website-targeted JavaScript Skin Designer integration

[liannacasper]

Motivation

• Provide a web-friendly JavaScript build of the existing Skin Designer so it can be embedded into the website similarly to the Playground and Initializr, and enable save/export flows in browser mode.

Description

• Add a website-native ShouldExecute implementation for the JavaScript port that returns true and posts a cn1-skindesigner-ui-ready message to the parent page to support embedded hosting (file: scripts/skindesigner/javascript/src/main/javascript/com_codename1_tools_skindesigner_ShouldExecute.js).
• Add a new site page and Hugo layout that embeds the JavaScript bundle at /skindesigner/ with loading UI and dark-mode sync (files: docs/website/content/skindesigner.md and docs/website/layouts/_default/skindesigner.html).
• Add a Developers menu entry for "Skin Designer" in docs/website/hugo.toml.
• Extend scripts/website/build.sh to optionally build and extract the Skin Designer JavaScript bundle into docs/website/static/skindesigner-app using WEBSITE_INCLUDE_SKINDESIGNER, following the same pattern used for Playground/Initializr.

Testing

• Ran bash -n scripts/website/build.sh which reported no syntax errors in the modified build script.
• Attempted to build the JavaScript module with sh ./mvnw -q -pl javascript -am -DskipTests -Dcodename1.platform=javascript package in scripts/skindesigner, but the build failed in this environment due to missing Java 8 (JAVA_HOME path not present) and network/maven wrapper download errors (java.net.SocketException: Network is unreachable).
• Changes were committed and a branch/PR message was prepared; no further automated tests were executed due to the environment limitations described above.

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Codex Task

[github-actions]

Cloudflare Preview

• URL: https://pr-4758-website-preview.codenameone.pages.dev
• Branch: pr-4758-website-preview