New Features
* #3586472 Use ai_provider_configuration form element in RestrictToTopic configuration form
* #3586500 Allow vector database providers to opt in as the default VDB when none is set
* #3586557 Support long running chunking in 1.x branch for AI Search 1.x readiness
* #3584977 RestrictToTopic guardrail: add semantic topic matching mode
* #3557016 Plugin shouldn't show any fields if no text is selected

Tasks
* #3566613 Require merge commits into main branches to include an issue reference in the format #[number], without restricting commit messages on feature branches
* #3477173 Add Functional Tests for AI CKEditor
* #3586488 Add a deterministic script to auto-generate the providers/operation-types matrix from GitLab

Bugs
* #3586522 Fiber branch in OpenAiBasedProviderClientBase::chat() drops token usage from the reconstructed ChatOutput
* #3585596 Prompt Library menu item missing due to incorrect parent
* #3586545 Issue when creating content and click on AI Assistant on Ckeditor
* #3575346 AI CKEditor: Hardcoded “summarize” message shown for all plugins when no text is selected
* #3584863 ImageClassificationItem returns string from getConfidenceScorePercentage and uses uppercase NULL in hints
* #3586574 Agent Skill 'create-ai-api-explorer' failed validation
* #3579979 Tools UI overview page does not load

Contributors:
a.dmitriiev, abhisekmazumdar, marcus_johansson, ahmad khader, jucs7, codeitwisely, drupov, kristen pol, sapatevaibhav, dpalicepeio@drupbuilder.org, cadence96, avinash.jha, annmarysruthy, svendecabooter, fago, scott_euser, hrishikesh-dalal, enriquelacoma, velmir_taky, akhil babu, jibran, prabha1997, ronaldtebrake, sapnil_biswas, damienmckenna, shubhamgoel, joshua1234511