ui: Add Thinking mode toggle with reasoning effort levels + improvements for Chat...

ui: Add Thinking mode toggle with reasoning effort levels + improvements for Chat Form Add Action UI (#23434)

* feat: Add "Thinking" toggle and status icon + redesign Chat Form Actions Add panel

* test: Update test reference

* fix: Icon

* fix: E2E test command

* fix: wait for greeting h1 to be visible in e2e test

* fix: remove duplicate PDF option in attachment dropdown

* fix: use label-based group toggle to avoid stale references

* refactor: inline MCP server and tool toggles in mobile sheet

* fix: serve correct build directory in e2e playwright config

* feat: add reasoning effort levels selector in model dropdown

* feat: Reasoning effort

* refactor: Make server origin configurable via environment variable

* feat: Add chat template thinking detector utility

* feat: Add thinking support detection to models store

* refactor: Update model selector components with thinking detection and message-specific indicators

* feat: Update chat form components for model selection and thinking support

* feat: Improve Reasoning controls UI

* refactor: Apply suggestions from code review

Co-authored-by: Aleksander Grygier <redacted>
* fix: Model tags

* refactor: Cleanup

* refactor: Remove unneeded components

* refactor: Cleanup