docs: add task-oriented feature guides
docs: sync wiki with current runtime behavior Update the wiki to match the shipped callback execution, structured output, export, and storage features. Refresh installation and data model details so the docs reflect the current 0.2 surface area.
docs: sync wiki with current main behavior Update the wiki to reflect current provider support, storage behavior, and run lifecycle details. Refresh the installation and quick start guides so they match the embedded and standalone flows on main.
docs: add Gemini provider references to wiki
Updated Quick Start (markdown)
Created Quick Start (markdown)