DOC-3404 - Update Full-Featured Premium Demo to use TinyMCE AI plugin

[kemister85]

Ticket: DOC-3404

Site: Staging branch

Changes:

• Replace legacy AI Assistant plugin (ai) with TinyMCE AI plugin (tinymceai) in full-featured premium demo
• Update toolbar buttons: aidialog aishortcuts replaced with tinymceai-chat, tinymceai-review, ai-quickactions-translate
• Update quickbar: add tinymceai-quickactions and ai-quickactions-translate alongside standard formatting items and addcomment
• Change default sidebar from Comments (showcomments) to AI Chat (tinymceai-chat)
• Add tinymceai_languages with 12 languages matching the TinyMCE AI plugin demo
• Add tinymceai_quickactions_custom with a "Challenge" action
• Add tinymceai_chat_fetch_sources and tinymceai_chat_fetch_source for documentation, blog, and survey resources
• Replace legacy ai_request callback and fetchEventSource dependency with tinymceai_token_provider
• Update demo HTML content: "an AI assistant" changed to "TinyMCE AI"
• Add AI Assistant to excluded plugins table (replaced by TinyMCE AI)

Files changed

• modules/ROOT/examples/live-demos/full-featured/index.js – Production demo config
• modules/ROOT/examples/live-demos/full-featured/example.js – Example code shown in docs
• modules/ROOT/examples/live-demos/full-featured/index.html – Demo HTML content
• modules/ROOT/pages/full-featured-premium-demo.adoc – Demo page (excluded plugins table)

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Pre-checks:

• Branch is correctly prefixed:

• Hotfix: hotfix/8/DOC-3404

• modules/ROOT/nav.adoc has been updated (if applicable).

• Files have been included where required (if applicable).

• Files removed have been deleted, not just excluded from the build (if applicable).

• Files added for New product features include a release note entry.

• Major or minor version changes have updated the supported-versions.adoc table.

• Build passes without console errors, warnings, or issues.

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Review:

• Documentation Team Lead has reviewed.