feat: rename service to galo, add halo branding and release build

- rename Go module, binary, systemd unit, PG_DATABASE default, frontend package and docs from shared-album to galo
- add theme-aware halo emblem and favicon (new ui-branding capability)
- add make build-release (versioned, stripped, static binary) and run the binary from the repo root

frontend/src/routes/(public)/+layout.svelte

@@ -1,6 +1,6 @@
 <script lang="ts">
 	import ThemeSwitcher from '$lib/components/ThemeSwitcher.svelte';
-	import Icon from '$lib/components/Icon.svelte';
+	import Emblem from '$lib/components/Emblem.svelte';
 
 	let { children } = $props();
 </script>
@@ -9,7 +9,7 @@
 	<header class="border-border bg-chrome border-b">
 		<div class="mx-auto flex max-w-6xl items-center justify-between px-4 py-3">
 			<a href="/" class="inline-flex items-center gap-2 text-lg font-semibold">
-				<Icon name="photo_camera" />
+				<Emblem class="text-primary size-6" />
 				Galo
 			</a>
 			<ThemeSwitcher />