Update all translation files with missing stock-related strings

Added 8 missing stock management translations to all locales:
- de_DE (German, formal): Stock strings with "auf Lager"
- de_DE_informal (German, informal): Stock strings with "auf Lager"
- de_CH (Swiss German, formal): Stock strings with "an Lager"
- de_CH_informal (Swiss German, informal): Stock strings with "an Lager"
- fr_CH (Swiss French): Stock strings with "en stock/rupture"

All translation files now complete with 55/55 strings:
- "\"%s\" is out of stock and cannot be selected."
- "Only %2$d of \"%1$s\" are available in stock."
- "Stock reduced for \"%1$s\": -%2$d (remaining: %3$d)"
- "Stock restored for \"%1$s\": +%2$d (total: %3$d)"
- "Out of stock"
- "Only"
- "left"
- "In stock"

Note: it_CH already had complete translations from v1.1.0

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

languages/wc-composable-product-de_DE.po

@@ -198,3 +198,35 @@ msgstr "Geben Sie Produkt-Artikelnummern durch Kommas getrennt ein."
 #: includes/Admin/Product_Data.php
 msgid "SKU-1, SKU-2, SKU-3"
 msgstr "ART-1, ART-2, ART-3"
+
+#: includes/Stock_Manager.php
+msgid "\"%s\" is out of stock and cannot be selected."
+msgstr "\"%s\" ist nicht auf Lager und kann nicht ausgewählt werden."
+
+#: includes/Stock_Manager.php
+msgid "Only %2$d of \"%1$s\" are available in stock."
+msgstr "Nur %2$d von \"%1$s\" sind auf Lager verfügbar."
+
+#: includes/Stock_Manager.php
+msgid "Stock reduced for \"%1$s\": -%2$d (remaining: %3$d)"
+msgstr "Lagerbestand reduziert für \"%1$s\": -%2$d (verbleibend: %3$d)"
+
+#: includes/Stock_Manager.php
+msgid "Stock restored for \"%1$s\": +%2$d (total: %3$d)"
+msgstr "Lagerbestand wiederhergestellt für \"%1$s\": +%2$d (gesamt: %3$d)"
+
+#: templates/product-selector.twig
+msgid "Out of stock"
+msgstr "Nicht auf Lager"
+
+#: templates/product-selector.twig
+msgid "Only"
+msgstr "Nur"
+
+#: templates/product-selector.twig
+msgid "left"
+msgstr "übrig"
+
+#: templates/product-selector.twig
+msgid "In stock"
+msgstr "Auf Lager"