fix(contacts): warn on unsupported dict/list email/tel update inputs

Surface the text-merge update path's limitation rather than silently no-op:
when contact_data['email'] or ['tel'] arrives as a dict/list on update, log a
warning at the top of _merge_vcard_properties pointing callers at plain str
or create_contact. Existing EMAIL/TEL lines are still preserved unchanged.

Bring nc_contacts_update_contact docstring into parity with create — the
update tool now documents the same keys plus the explicit single-string
limitation for email/tel and the BDAY validation / URL first-only behaviours.

Three new TestMergeVcardProperties cases pin the warning: dict email warns,
list tel warns, plain str email is silent (no false positives).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

nextcloud_mcp_server/client/contacts.py

@@ -482,7 +482,29 @@ class ContactsClient(BaseNextcloudClient):
     def _merge_vcard_properties(
         self, raw_vcard: str, contact_data: dict[str, Any], uid: str
     ) -> str:
-        """Merge new contact data into existing raw vCard while preserving all properties."""
+        """Merge new contact data into existing raw vCard while preserving all properties.
+
+        Limitation: dict / list-form ``email`` and ``tel`` inputs are not applied
+        by this text-merge path. Existing EMAIL/TEL lines are preserved unchanged,
+        and no new lines are written for the dict/list inputs. Pass plain strings
+        to update EMAIL/TEL here, or recreate via ``create_contact`` for full
+        multi-entry support with TYPE annotations.
+        """
+        # Surface dict/list email/tel up front rather than silently no-op in the
+        # add-new loop below (where the isinstance(value, str) guard skips them).
+        for _key in ("email", "tel"):
+            _value = contact_data.get(_key)
+            if _value is not None and not isinstance(_value, str):
+                logger.warning(
+                    "update_contact: %s=%r (dict/list shape) is not applied via "
+                    "the text-merge update path; existing %s lines are preserved "
+                    "unchanged. Use a plain string to update %s here, or recreate "
+                    "via create_contact for multi-entry support.",
+                    _key,
+                    _value,
+                    _key.upper(),
+                    _key.upper(),
+                )
         try:
             # Instead of using pythonvCard4 which has formatting issues,
             # let's do a simple text-based merge to preserve exact formatting