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 <aleksander.grygier@gmail.com>

* fix: Model tags

* refactor: Cleanup

* refactor: Remove unneeded components

* refactor: Cleanup

tools/ui/tests/e2e/demo.test.ts

@@ -1,6 +1,7 @@
 import { expect, test } from '@playwright/test';
 
-test('home page has expected h1', async ({ page }) => {
+test('home page loads correctly', async ({ page }) => {
 	await page.goto('/');
-	await expect(page.locator('h1').first()).toBeVisible();
+	// Wait for the greeting to become visible (stores need time to initialize)
+	await expect(page.locator('h1', { hasText: /Hello there/ })).toBeVisible();
 });

tools/ui/tests/stories/ChatScreenForm.a11y.stories.svelte

@@ -44,7 +44,7 @@
 		await screen.findByRole('menu');
 
 		await waitFor(() => {
-			expect(document.activeElement).toHaveTextContent('Text Files');
+			expect(document.activeElement).toHaveTextContent('Add files');
 		});
 	}}
 />