feat(dav): expand_rrule + dav_make_calendar para recurrencia y multi-calendario

Dos funciones nuevas del grupo de capacidad `dav`:
- expand_rrule_py_infra (pure): expande una RRULE iCalendar a las fechas de
  cada ocurrencia dentro de un rango [from, to]. Solo stdlib (datetime, re).
  Soporta FREQ DAILY/WEEKLY/MONTHLY/YEARLY, INTERVAL, COUNT, UNTIL, BYDAY. 9 tests.
- dav_make_calendar_py_infra (impure): crea una coleccion de calendario nueva
  via MKCALENDAR + PROPPATCH de nombre/color. Idempotente si ya existe. 11 tests.

Consumidas por la app osint_web (eventos recurrentes + creacion de agendas).
Pagina del grupo dav actualizada con ambas.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

python/functions/infra/expand_rrule_test.py

@@ -0,0 +1,144 @@
+"""Tests para expand_rrule."""
+
+import os
+import sys
+
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), "..", ".."))
+
+from functions.infra.expand_rrule import expand_rrule
+
+
+def test_golden_weekly_count_4():
+    # FREQ=WEEKLY;COUNT=4 a partir del 2026-01-05 (lunes) -> 4 fechas a 7 dias.
+    got = expand_rrule(
+        "20260105T090000",
+        "FREQ=WEEKLY;COUNT=4",
+        "20260101",
+        "20261231",
+    )
+    assert got == [
+        "20260105T090000",
+        "20260112T090000",
+        "20260119T090000",
+        "20260126T090000",
+    ]
+
+
+def test_edge_monthly_interval_2():
+    # INTERVAL=2 mensual: cada dos meses, dia 15.
+    got = expand_rrule(
+        "20260115",
+        "FREQ=MONTHLY;INTERVAL=2;COUNT=4",
+        "20260101",
+        "20261231",
+        all_day=True,
+    )
+    assert got == ["20260115", "20260315", "20260515", "20260715"]
+
+
+def test_edge_weekly_byday_two_days():
+    # BYDAY con 2 dias en WEEKLY: MO y WE, dentro de cada semana del intervalo.
+    # dtstart 2026-01-05 (lunes). COUNT=4 -> MO,WE de la sem 1 y MO,WE de la sem 2.
+    got = expand_rrule(
+        "20260105",
+        "FREQ=WEEKLY;BYDAY=MO,WE;COUNT=4",
+        "20260101",
+        "20261231",
+        all_day=True,
+    )
+    assert got == ["20260105", "20260107", "20260112", "20260114"]
+
+
+def test_edge_all_day_vs_with_time():
+    # all_day=True -> YYYYMMDD; all_day=False conserva la hora del dtstart.
+    all_day = expand_rrule(
+        "20260105T143000",
+        "FREQ=DAILY;COUNT=2",
+        "20260101",
+        "20261231",
+        all_day=True,
+    )
+    assert all_day == ["20260105", "20260106"]
+
+    with_time = expand_rrule(
+        "20260105T143000",
+        "FREQ=DAILY;COUNT=2",
+        "20260101",
+        "20261231",
+        all_day=False,
+    )
+    assert with_time == ["20260105T143000", "20260106T143000"]
+
+
+def test_until_recorta():
+    # UNTIL=20260120 recorta la serie semanal inclusive en esa fecha.
+    got = expand_rrule(
+        "20260105T090000",
+        "FREQ=WEEKLY;UNTIL=20260120T235959Z",
+        "20260101",
+        "20261231",
+    )
+    assert got == [
+        "20260105T090000",
+        "20260112T090000",
+        "20260119T090000",
+    ]
+
+
+def test_filtro_por_rango_excluye_fuera():
+    # COUNT=10 semanal, pero el rango solo cubre 3 ocurrencias intermedias.
+    got = expand_rrule(
+        "20260105T090000",
+        "FREQ=WEEKLY;COUNT=10",
+        "20260112",
+        "20260131",
+    )
+    assert got == [
+        "20260112T090000",
+        "20260119T090000",
+        "20260126T090000",
+    ]
+
+
+def test_dtstart_anterior_al_rango_pero_serie_entra():
+    # dtstart en 2025-12-29 (antes del rango), serie semanal entra en enero 2026.
+    got = expand_rrule(
+        "20251229T090000",
+        "FREQ=WEEKLY;COUNT=8",
+        "20260101",
+        "20260115",
+    )
+    assert got == [
+        "20260105T090000",
+        "20260112T090000",
+    ]
+
+
+def test_componente_no_soportado_se_ignora():
+    # BYMONTHDAY no soportado -> se ignora, no falla. Serie mensual normal.
+    got = expand_rrule(
+        "20260110",
+        "FREQ=MONTHLY;BYMONTHDAY=10;COUNT=3",
+        "20260101",
+        "20261231",
+        all_day=True,
+    )
+    assert got == ["20260110", "20260210", "20260310"]
+
+
+def test_sin_count_ni_until_acota_a_range_end():
+    # Sin COUNT ni UNTIL: la generacion debe acotarse por range_end.
+    got = expand_rrule(
+        "20260101",
+        "FREQ=DAILY",
+        "20260101",
+        "20260105",
+        all_day=True,
+    )
+    assert got == [
+        "20260101",
+        "20260102",
+        "20260103",
+        "20260104",
+        "20260105",
+    ]