Localization (#1)

Implement comprehensive content localization, admin panels for editing each language, AI translation interface with automatic updates when base language version is changed.
- SEO tags for all language URLs
- Uses accept-language by default, ?lang=en overrides temporarily
- User edits patched on top of translations
- RTL language supportReviewed-on: https://git.zi.fi/LeoVasanko/pagerite/pulls/1

frontend/src/ConnNote.vue

@@ -0,0 +1,21 @@
+<script setup>
+// Connection-state note for the WebSocket-backed panels (page/banner
+// editors, analytics view): while the socket is connecting or waiting to
+// reconnect the panel cannot load or save, and this says so. An empty
+// text hides the note.
+defineProps({ text: { type: String, default: '' } })
+</script>
+
+<template>
+  <div v-if="text" class="conn-note" role="status">{{ text }}</div>
+</template>
+
+<style scoped>
+.conn-note {
+  padding: 0.2rem 1rem;
+  border-bottom: 1px solid var(--line);
+  background: var(--surface);
+  color: var(--muted);
+  font-size: 0.8rem;
+}
+</style>