allozaur/feat/chat slash commands (#26716)

* base : slash-command/misc foundation - model icon and focus-selector constants

* feat : slash-command picker and command parsing helpers

* refactor : wire command and @-mention pickers into the chat form

* ui : improve model selector keyboard navigation and load/dismiss

* feat: Unify markdown/raw-text rendering under one setting with migration

* fix: Misc fixes - tool-call subtitle, assistant wrap, progress guards

* feat: Clamp and style numeric settings inputs from registry bounds

tools/ui/tests/unit/command-token.test.ts

@@ -0,0 +1,51 @@
+import { describe, expect, it } from 'vitest';
+import { findCommandToken, takeCommandDismissSnapshot } from '$lib/utils';
+
+describe('findCommandToken', () => {
+	it('returns null when the value does not start with a slash', () => {
+		expect(findCommandToken('hello /prompt')).toBeNull();
+		expect(findCommandToken('')).toBeNull();
+		expect(findCommandToken('prompt')).toBeNull();
+	});
+
+	it('parses a bare slash', () => {
+		expect(findCommandToken('/')).toEqual({ name: '', args: '', end: 1 });
+	});
+
+	it('parses a command name with no args', () => {
+		expect(findCommandToken('/prompt')).toEqual({ name: 'prompt', args: '', end: 7 });
+	});
+
+	it('parses a command name followed by a space', () => {
+		expect(findCommandToken('/prompt ')).toEqual({ name: 'prompt', args: '', end: 8 });
+	});
+
+	it('parses args after the command name', () => {
+		expect(findCommandToken('/prompt rev')).toEqual({ name: 'prompt', args: 'rev', end: 11 });
+	});
+
+	it('parses multi-word args', () => {
+		expect(findCommandToken('/prompt  review  code ')).toEqual({
+			name: 'prompt',
+			args: ' review  code ',
+			end: 22
+		});
+	});
+
+	it('treats the whole run as the name when there is no space', () => {
+		expect(findCommandToken('/promptx')).toEqual({ name: 'promptx', args: '', end: 8 });
+	});
+});
+
+describe('takeCommandDismissSnapshot', () => {
+	it('returns null when there is no command token', () => {
+		expect(takeCommandDismissSnapshot('hello')).toBeNull();
+	});
+
+	it('captures the name and args', () => {
+		expect(takeCommandDismissSnapshot('/prompt rev')).toEqual({
+			name: 'prompt',
+			args: 'rev'
+		});
+	});
+});