feat(dav,obsidian): grupo dav completo (CardDAV/CalDAV client + split vcf/ics + import pipelines) + build_obsidian_graph + dav_list_calendars

Funciones reutilizables creadas esta sesion para el sistema self-hosted de contactos/calendario (Xandikos) y la app osint_web:
- grupo dav (infra): split_vcards, split_vevents_to_vcalendars, extract_or_make_uid, carddav_put_vcard, caldav_put_event, dav_list_resources, dav_get_resource, dav_list_calendars
- pipelines: import_vcf_to_carddav, import_ics_to_caldav
- obsidian: build_obsidian_graph (grafo agregado del vault)

python/functions/infra/split_vcards_test.py

@@ -0,0 +1,40 @@
+"""Tests para split_vcards. Puros, deterministas, sin I/O."""
+
+import sys
+
+import infra.split_vcards  # noqa: F401
+
+mod = sys.modules["infra.split_vcards"]
+split_vcards = mod.split_vcards
+
+_TWO = (
+    "BEGIN:VCARD\r\nVERSION:3.0\r\nFN:Ada Lovelace\r\nEND:VCARD\r\n"
+    "BEGIN:VCARD\r\nVERSION:3.0\r\nFN:Alan Turing\r\nEND:VCARD\r\n"
+)
+
+
+def test_dos_vcards_devuelve_dos():
+    cards = split_vcards(_TWO)
+    assert len(cards) == 2
+
+
+def test_vcard_unico():
+    cards = split_vcards("BEGIN:VCARD\nFN:Solo\nEND:VCARD\n")
+    assert len(cards) == 1
+    assert "Solo" in cards[0]
+
+
+def test_input_vacio_devuelve_lista_vacia():
+    assert split_vcards("") == []
+    assert split_vcards("ruido sin tarjetas") == []
+
+
+def test_crlf_se_tolera():
+    lf = _TWO.replace("\r\n", "\n")
+    assert len(split_vcards(lf)) == 2
+
+
+def test_cada_card_es_begin_end():
+    for c in split_vcards(_TWO):
+        assert c.startswith("BEGIN:VCARD")
+        assert c.endswith("END:VCARD")