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/server/contacts.py

@@ -250,7 +250,30 @@ def configure_contacts_tools(mcp: FastMCP):
                 not the display name. Use nc_contacts_list_addressbooks to
                 find available URI slugs.
             uid: The unique ID of the contact to update.
-            contact_data: A dictionary with the contact's updated details, e.g. {"fn": "Jane Doe", "email": "jane.doe@example.com"}.
+            contact_data: A dictionary with the contact's updated details. Supported
+                keys mirror nc_contacts_create_contact:
+
+                - ``fn`` (str): Formatted full name.
+                - ``email`` (str): Email address. **Update path supports plain
+                  strings only**; dict / list-form inputs are not applied — the
+                  existing EMAIL line is preserved unchanged and a warning is
+                  logged. Use create_contact for multi-entry support with TYPE
+                  annotations.
+                - ``tel`` / ``phone`` (str): Phone number. Same single-string
+                  limitation as ``email`` above.
+                - ``org`` / ``organization`` (str or list of str): Organization.
+                  Lists become semicolon-separated ORG components per RFC 6350.
+                - ``title`` (str): Job title.
+                - ``note`` (str): Free-form note.
+                - ``nickname`` (str or list of str).
+                - ``bday`` (ISO date str ``"YYYY-MM-DD"`` or ``datetime.date``).
+                  Non-ISO strings are rejected with a warning; the existing
+                  BDAY line is preserved.
+                - ``categories`` (list of str, or comma-separated str).
+                - ``url`` (str or list of str). Only the first URL is written
+                  on update; multi-URL contacts should use create_contact.
+
+                Example: ``{"fn": "Jane Doe", "email": "jane.doe@example.com"}``.
             etag: Optional ETag for optimistic concurrency control.
         """
         client = await get_client(ctx)