fix: ffmpeg/yt-dlp/tz in image, UID 1000, reactive accent store

- runtime: use node user (uid=1000, gid=1000) instead of custom tonemark uid=1001
- add ffmpeg and yt-dlp to runtime image (required by audio pipeline)
- add tzdata, set TZ=Europe/Zurich
- +page.svelte: replace hardcoded ACCENT constant with $derived($accent.value)
  so the home page reacts to accent store changes from Settings

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/routes/+page.svelte

@@ -4,8 +4,9 @@
 	import SourceIcon from '$lib/components/SourceIcon.svelte';
 	import Waveform from '$lib/components/Waveform.svelte';
 	import RecordButton from '$lib/components/RecordButton.svelte';
+	import { accent } from '$lib/accent.js';
 
-	const ACCENT = '#cdf24e';
+	const ACCENT = $derived($accent.value);
 
 	let url = $state('');
 	let audioMode = $state<AudioMode>('auto');