feat(client): add component library and simplify routing (#66)

* feat(client): add component library and simplify routing

Remove tab layout, explore page, modal, and unused template
components. Replace with single-page layout and a dev component
showcase with per-component detail pages.

- Add Button with label prop, leading/trailing icon support
- Add FeedCard, SerifText, SansSerifText, MonospaceText
- Add colocated *.showcase.tsx files for each component
- Use Stack navigator with themed headers

Co-authored-by: Ona <no-reply@ona.com>

* fix(client): render showcase as JSX component

Co-authored-by: Ona <no-reply@ona.com>

* chore(client): remove dead code chain

Remove ThemedText, useThemeColor, useColorScheme hook,
Colors, and Fonts — none referenced by current screens.

Co-authored-by: Ona <no-reply@ona.com>

---------

Co-authored-by: Ona <no-reply@ona.com>

apps/aelis-client/src/app/index.tsx

@@ -0,0 +1,28 @@
+import { Link } from "expo-router"
+import { Pressable } from "react-native"
+import { SafeAreaView } from "react-native-safe-area-context"
+import tw from "twrnc"
+
+import { Button } from "@/components/ui/button"
+import { FeedCard } from "@/components/ui/feed-card"
+import { MonospaceText } from "@/components/ui/monospace-text"
+import { SansSerifText } from "@/components/ui/sans-serif-text"
+import { SerifText } from "@/components/ui/serif-text"
+
+export default function HomeScreen() {
+	return (
+		<SafeAreaView style={tw`bg-stone-100 dark:bg-stone-900 flex-1 px-5 pt-6 gap-4`}>
+			<FeedCard>
+				<SerifText style={tw`text-4xl`}>Hello world asdsadsa</SerifText>
+				<SansSerifText style={tw`text-4xl font-bold`}>Hello world</SansSerifText>
+				<MonospaceText style={tw`text-4xl`}>asdjsakljdl</MonospaceText>
+				<Button style={tw`self-start`} label="Test" />
+			</FeedCard>
+			<Link href="/components" asChild>
+				<Pressable>
+					<SansSerifText style={tw`text-teal-600`}>View component library</SansSerifText>
+				</Pressable>
+			</Link>
+		</SafeAreaView>
+	)
+}