feat(frontend): add PL/EN i18n using @inlang/paraglide-js v2

- Install @inlang/paraglide-js v2 with Vite plugin and paraglideMiddleware hook
- Add messages/pl.json and messages/en.json with ~400 translation keys
- Create project.inlang/settings.json (PL as base locale)
- Add LanguageSwitcher component (cookie-based, no URL prefix needed)
- Replace all hardcoded strings across 14 pages/components with m.*() calls
- ProductForm uses derived label maps for all enum types (category, texture, etc.)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/routes/routines/new/+page.svelte

@@ -1,6 +1,7 @@
 <script lang="ts">
 	import { enhance } from '$app/forms';
 	import type { ActionData, PageData } from './$types';
+	import { m } from '$lib/paraglide/messages.js';
 	import { Button } from '$lib/components/ui/button';
 	import { Input } from '$lib/components/ui/input';
 	import { Label } from '$lib/components/ui/label';
@@ -11,12 +12,12 @@
 	let partOfDay = $state('am');
 </script>
 
-<svelte:head><title>New Routine — innercontext</title></svelte:head>
+<svelte:head><title>{m["routines_newTitle"]()} — innercontext</title></svelte:head>
 
 <div class="max-w-md space-y-6">
 	<div class="flex items-center gap-4">
-		<a href="/routines" class="text-sm text-muted-foreground hover:underline">← Routines</a>
-		<h2 class="text-2xl font-bold tracking-tight">New Routine</h2>
+		<a href="/routines" class="text-sm text-muted-foreground hover:underline">{m["routines_backToList"]()}</a>
+		<h2 class="text-2xl font-bold tracking-tight">{m["routines_newTitle"]()}</h2>
 	</div>
 
 	{#if form?.error}
@@ -24,16 +25,16 @@
 	{/if}
 
 	<Card>
-		<CardHeader><CardTitle>Routine details</CardTitle></CardHeader>
+		<CardHeader><CardTitle>{m["routines_detailsTitle"]()}</CardTitle></CardHeader>
 		<CardContent>
 			<form method="POST" use:enhance class="space-y-5">
 				<div class="space-y-2">
-					<Label for="routine_date">Date *</Label>
+					<Label for="routine_date">{m.routines_date()}</Label>
 					<Input id="routine_date" name="routine_date" type="date" value={data.today} required />
 				</div>
 
 				<div class="space-y-2">
-					<Label>AM or PM *</Label>
+					<Label>{m["routines_amOrPm"]()}</Label>
 					<input type="hidden" name="part_of_day" value={partOfDay} />
 					<Select type="single" value={partOfDay} onValueChange={(v) => (partOfDay = v)}>
 						<SelectTrigger>{partOfDay.toUpperCase()}</SelectTrigger>
@@ -45,13 +46,13 @@
 				</div>
 
 				<div class="space-y-2">
-					<Label for="notes">Notes</Label>
-					<Input id="notes" name="notes" placeholder="Optional notes" />
+					<Label for="notes">{m.routines_notes()}</Label>
+					<Input id="notes" name="notes" placeholder={m["routines_notesPlaceholder"]()} />
 				</div>
 
 				<div class="flex gap-3 pt-2">
-					<Button type="submit">Create routine</Button>
-					<Button variant="outline" href="/routines">Cancel</Button>
+					<Button type="submit">{m["routines_createRoutine"]()}</Button>
+					<Button variant="outline" href="/routines">{m.common_cancel()}</Button>
 				</div>
 			</form>
 		</CardContent>