feat(platform): live-wire AGB v2 + DSE v3 + Architektur-Tab (#29)

AGB v2 (decision_method routing, 71%FP->~0) + DSE v3 (4-layer, recovered from container) + Architektur-Tab into /sdk/agent live path. Incl CI robustness (detect-changes.sh + PR-head checkout) + security (hardcoded Qdrant key removed, gitleaks allowlist).

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

backend-compliance/compliance/tests/test_agb_agent.py

@@ -1,12 +1,27 @@
-"""AGBAgent — kuratierte §§-305-ff-BGB-Checkliste (ChecklistAgent-Subclass)."""
-
-from __future__ import annotations
-
+"""AGBAgent (v2, routed). Embedding/LLM offline-gestubbt → kein Netzwerk."""
 import asyncio
 
+import pytest
+
+import compliance.services.specialist_agents.agb._pipeline as pipeline
+from compliance.services.checkers.base import CheckResult
 from compliance.services.specialist_agents import REGISTRY, AgentInput
 
 
+class _Stub:
+    def __init__(self, present):
+        self._p = present
+
+    async def check(self, ctrl, doc):
+        return CheckResult(present=self._p)
+
+
+@pytest.fixture(autouse=True)
+def _offline(monkeypatch):
+    monkeypatch.setattr(pipeline, "_EMB", _Stub(None))
+    monkeypatch.setattr(pipeline, "_LLM", _Stub(None))
+
+
 def _run(text: str):
     return asyncio.run(
         REGISTRY.get("agb").evaluate(AgentInput(doc_type="agb", text=text)))