[ZEPPELIN-6564] Route the published paragraph through the shared react-mount loader

[voidmatcha]

What is this PR for?

Moves the published paragraph off its own React loader and onto the shared react-mount directive, and removes the dead Module Federation configuration that this exposed.

Today there are two loaders. published/paragraph.component.ts injects a script tag into document.head and reads window.reactApp directly, while the paragraph footer goes through the [zeppelin-react-mount] directive added in ZEPPELIN-6428. The two paths differ in load-failure handling, container caching and typing. The bespoke path has no fallback at all, so a published paragraph whose remote fails to load renders nothing.

Split into four commits.

1. Remove dead Module Federation configuration

The shell webpack.config.js declares a reactApp remote but never calls container.init and never bundles React. Also removes the GenerateRemoteEntryJson plugin, which writes a remoteEntry.json nothing reads, and the unused @angular-architects/module-federation and ngx-build-plus devDependencies. As a side effect the hard-coded reactApp@http://localhost:3001/remoteEntry.js no longer ends up in production shell bundles.

2. Make @zeppelin/sdk framework-neutral

The SDK declares @angular/common and @angular/core as peerDependencies but imports neither, and pins them at ^8.2.9 while the project is on Angular 21. It does use rxjs, which is not declared. A non-Angular consumer, which is what the React remote is, inherits a requirement that does not exist and misses one that does.

3. Add ReactFeatureService as the single flag resolver

Flag parsing was split. The published paragraph accepted both ?react=true and a bare ?react, while notebook.component.ts required exactly ?reactFooter=true. Unified on the permissive rule so the URLs documented in ZEPPELIN-6371 keep working. As a result a bare ?reactFooter now enables the footer as well. Both flags are experimental opt-ins; with no flag the behaviour is unchanged.

4. Route the published paragraph through the shared react-mount loader

Moves the component onto the directive and makes ./PublishedParagraph satisfy the mount contract. It previously returned a bare unmount function, which the directive classified as legacy and for which it made update a no-op.

What type of PR is it?

Refactoring

Todos

None

What is the Jira issue?

https://issues.apache.org/jira/browse/ZEPPELIN-6564

How should this be tested?

• A production build.
• The zeppelin-react vitest suite, extended with a mount-contract spec for PublishedParagraph mirroring the existing ParagraphFooter one. It covers the handle shape, in-place update within the same subtree, the empty-state round trip, and onError on a render failure.
• The Playwright suites for the published paragraph and the paragraph footer, including the fallback path on both.
• The Angular shell has no unit test harness (ZEPPELIN-6566, ZEPPELIN-6567), so its side is covered by Playwright only.

Screenshots (if appropriate)

No

Questions:

• Does the license files need to update? No
• Is there breaking changes for older versions? No
• Does this needs documentation? Yes