feat(agent): Impressum Rechtsform-Gates + USt-optional (Phase 3)

Die 8 Audit-Klassifizierungs-Felder (scan_context) treiben jetzt den
business_scope der Agenten (vorher gespeichert, aber nicht genutzt).
Rechtsform-Gates als opt-out (excludes_scope): Verein -> kein
Handelsregister-Finding, e.K. -> kein Vertretungsberechtigte-Finding;
unbekannte Rechtsform bleibt anwendbar. USt-IdNr optional -> fehlt =
kein Finding. Rechts-Zuordnung vom Domain-Experten bestaetigt.

- _classification.py: scan_context_to_scope (8 Felder -> scope-Tokens)
- mcs.py: MC.excludes_scope + MC.optional; IMP-MC-004/006 Gate-Tokens;
  IMP-MC-005 optional; scope_matches respektiert excludes_scope
- agent.py: optional -> kein Finding bei Abwesenheit
- _agent_outputs.py: scope = scan_context vereinigt LLM-Profil-Fallback
- Tests gruen: v3 25, Groundtruth 13, CI-Pfad 14 (+ SSE-Loop-Fix)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend-compliance/compliance/tests/test_sse_compliance_check.py

@@ -1,7 +1,7 @@
 """Phase 2: SSE-Plumbing für den Compliance-Check.
 
-Deckt emit (Queue-Push), _format_sse (SSE-Zeilenformat) und den
-event_generator (hello → Events → stream_close bei 'complete') ab.
+Queue + Generator laufen innerhalb eines asyncio.run (sonst bindet
+asyncio.Queue in Py3.9 an einen ggf. geschlossenen Loop).
 """
 
 from __future__ import annotations
@@ -11,15 +11,8 @@ import asyncio
 from compliance.api.agent_check import _sse
 
 
-def test_emit_pushes_and_format():
-    cid = "sse-test-1"
-    _sse.new_queue(cid)
-    _sse.emit(cid, {"type": "topic", "topic": "impressum", "output": {"x": 1}})
-    q = _sse._check_queues[cid]
-    assert q.qsize() == 1
-    ev = q.get_nowait()
-    assert ev["type"] == "topic" and ev["topic"] == "impressum"
-    line = _sse._format_sse(ev)
+def test_format_sse_line():
+    line = _sse._format_sse({"type": "topic", "topic": "impressum"})
     assert line.startswith("data: ") and line.endswith("\n\n")
     assert '"impressum"' in line
 
@@ -29,21 +22,20 @@ def test_emit_is_noop_without_queue():
     _sse.emit("does-not-exist-xyz", {"type": "topic"})
 
 
-def test_event_generator_streams_topic_then_closes_on_complete():
-    cid = "sse-test-gen"
-    _sse.new_queue(cid)
-    _sse.emit(cid, {"type": "topic", "topic": "impressum", "output": {}})
-    _sse.emit(cid, {"type": "complete", "status": "completed"})
-
-    async def collect():
-        out = []
+def test_emit_and_event_generator_streams_then_closes():
+    async def scenario():
+        cid = "sse-test-gen"
+        _sse.new_queue(cid)
+        _sse.emit(cid, {"type": "topic", "topic": "impressum", "output": {}})
+        _sse.emit(cid, {"type": "complete", "status": "completed"})
+        out: list[str] = []
         async for line in _sse.event_generator(cid):
             out.append(line)
             if len(out) > 12:  # safety
                 break
         return out
 
-    blob = "".join(asyncio.run(collect()))
+    blob = "".join(asyncio.run(scenario()))
     assert '"type": "hello"' in blob
     assert '"topic": "impressum"' in blob
     assert '"type": "complete"' in blob