Resolve "Migrate the ECA agent to the Tools + ReAct architecture (create-only)"

Closes #3585017

What changes:

• Uses the new config system, but it is still using the same ID, so anyone using it in an assistant or somewhere else will still use the new agent.
• Update hook (even if we are not stable).
• 5 new function calls needed for this with proper permissions - this is for 1.x branch and doesn't use Tool API.
• Services moved out for the function call to use.
• A lot of test for determenistic stuff
• A eval to see what can be solved and what not, see https://git.drupalcode.org/project/ai_integration_eca/-/blob/2152bd43ca193e3d431932d22dc02496ad8eb9cf/modules/agents/eval/results/2026-07-29-gpt-5.2.md
• Updated to 3.1 requirement and modeler api 1.1 requirement.

Question - should we actually require AI Agents? It could be fetched for anyone wanting the submodule?