fix(i18n): add backward-compat un-namespaced keys for module translations

Module i18n keys are namespaced (e.g. docsight.journal.icon_auto) but
existing JS code references them without prefix (T.icon_auto). Merge
both namespaced and un-namespaced keys to prevent JS errors.

Author: itsDNNS

app/module_loader.py

@@ -219,6 +219,9 @@ def merge_module_i18n(module_id: str, i18n_dir: str) -> None:
             if key.startswith("_"):
                 continue  # skip metadata keys like _meta
             _TRANSLATIONS[lang][f"{module_id}.{key}"] = value
+            # Also add un-namespaced key for backward compat with JS code
+            if key not in _TRANSLATIONS[lang]:
+                _TRANSLATIONS[lang][key] = value
 
         log.debug("Merged %d i18n keys for module '%s' lang '%s'", len(data), module_id, lang)