harden: per-item robustness + deadlines/caps across connectors; layered tests

Mail: _safe_decode + _iter_messages (per-mail try/except) -> eine kaputte Mail
(charset x-unknown) bricht die Suche nicht mehr ab, findet so auch uralte Mails.
Vollscan + Datum-Sort + MAX_SCAN/DEADLINE_S (Selbstheilung, kein 24h-Haenger mehr).

Files: search_files mit SEARCH_DEADLINE_S + SEARCH_MAX_DIRS begrenzt (war
unbegrenzte rekursive PROPFIND -> real 35s/449 Calls).

Calendar/Contacts: PARSE_DEADLINE_S fuer client-seitiges vobject-Parsen;
MAX_RESULTS-Output-Cap in get_events/get_tasks (war 10939 Zeilen bei 6000 Events);
search Top-N + Hinweise.

Tests: in Schichten getrennt -> Smoke (nightly), Edge + Stress (on-demand).
Neu: test_smoke/test_edge/test_stress + conftest-Marker + run_full_tests.sh,
nightly laeuft nur Smoke. Kontakt-Foto-Roundtrip-Test, Mail-Edge-Mails
(x-unknown, kaputter Header, 2009er Alt-Mail).

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

tests/test_smoke.py

@@ -0,0 +1,53 @@
+#!/usr/bin/env python3
+"""MCP Smoke-Tests — NIGHTLY.
+
+Minimal, schnell, read-only. Pro Connector: Server erreichbar, OAuth ok,
+tools/list ok, ein billiger Read-Call. Faengt Totalausfaelle (Server down,
+Auth kaputt, Backend weg) ueber Nacht ab, ohne Last zu erzeugen oder Testdaten
+zu schreiben.
+
+Lauf:  /opt/mcp-servers/venv/bin/python -m pytest test_smoke.py -q
+"""
+
+import pytest
+
+from test_all import SERVERS, get_token, mcp_call, tool_call
+
+pytestmark = pytest.mark.smoke
+
+
+@pytest.mark.parametrize("svc,port", list(SERVERS.items()))
+def test_server_up_auth_tools(svc, port):
+    """Server erreichbar + OAuth (client_credentials) + tools/list liefert Tools."""
+    token = get_token(port)
+    assert token, f"{svc}: kein Token"
+    res = mcp_call(port, token, "tools/list")
+    assert res and res.get("result", {}).get("tools"), f"{svc}: tools/list leer"
+
+
+# --- ein billiger Read-Call pro Connector (read-only, kein Schreiben) ---
+
+def test_mail_read():
+    assert "mcp-test-mail" in tool_call(SERVERS["mail"], get_token(SERVERS["mail"]), "list_accounts")
+
+
+def test_calendar_read():
+    text = tool_call(SERVERS["calendar"], get_token(SERVERS["calendar"]), "list_calendars")
+    assert "calendar-test" in text or "MCP Test" in text
+
+
+def test_contacts_read():
+    # read-only Suche; Treffer egal, Hauptsache der Call kommt sauber durch
+    text = tool_call(SERVERS["contacts"], get_token(SERVERS["contacts"]),
+                     "search_contacts", {"query": "Mustermann", "limit": 1})
+    assert isinstance(text, str) and len(text) >= 0
+
+
+def test_files_read():
+    text = tool_call(SERVERS["files"], get_token(SERVERS["files"]), "list_files", {"path": "/"})
+    assert "DIR" in text or "/" in text
+
+
+def test_notes_read():
+    text = tool_call(SERVERS["notes"], get_token(SERVERS["notes"]), "list_notebooks")
+    assert "id:" in text