task: #3623916 Add an AI agent for each component

Closes #3623916

An AI agent for each component, on top of the shared agents and skills.

Each agent is written for one component: it carries that component's real variants, slots and props from its manifest, and is told to ask display_builder_ai:get_component_details before it places anything, so the tool wins when the manifest and the code disagree.

They ship as config entities in config/optional, so they install where ai_agents and display_builder_ai are present, and stay out of the way where they are not.

AI-Generated: Yes

Checkpoints

• Issue created with a clear summary
• Merge request opened against 1.0.x
• CI pipeline passes