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/services/checkers/embedding_checker.py

@@ -0,0 +1,51 @@
+"""CONTENT-Pruefer / decision_method=EMBEDDING.
+
+Ist die Pflicht SEMANTISCH im Text vorhanden? Max-Cosinus (Doc-Chunks x Control-
+Paraphrasen) >= per-Control-Schwelle. Deterministisch (festes Embedding-Modell)
+und gecacht. Rettet Recall-FP (Klausel da, anders formuliert).
+
+Faellt der Embedding-Service aus, liefert der Checker present=None (unklar) — der
+Aufrufer behaelt dann das Keyword-Ergebnis (kein Hang, kein Crash).
+(Validiert an AGB: 17 Items, per-Item-Schwelle, 0 Fehl-Rescue.)
+"""
+from __future__ import annotations
+
+import asyncio
+import logging
+
+from .base import CheckResult, ControlSpec, DocContext, VerificationMethod
+
+logger = logging.getLogger(__name__)
+
+# Paraphrasen-Vektoren je Control einmal einbetten + cachen.
+_PARA_CACHE: dict[str, list] = {}
+
+
+class EmbeddingChecker:
+    verification_method = VerificationMethod.CONTENT
+
+    async def check(self, ctrl: ControlSpec, doc: DocContext) -> CheckResult:
+        text = doc.text or ""
+        paras = ctrl.paraphrases or []
+        thr = ctrl.embed_threshold if ctrl.embed_threshold is not None else 0.60
+        if not paras or len(text) < 100:
+            return CheckResult(present=None, source="embedding")
+        try:
+            from compliance.services.mc_embedding_matcher import (
+                DIM, _chunk_text, _cosine, _embed_texts,
+            )
+            if ctrl.control_id not in _PARA_CACHE:
+                pv = await _embed_texts(paras)
+                _PARA_CACHE[ctrl.control_id] = [v for v in pv if v and len(v) == DIM]
+            pvecs = _PARA_CACHE[ctrl.control_id]
+            chunks = _chunk_text(text)
+            cvecs = [v for v in await asyncio.wait_for(
+                _embed_texts(chunks), timeout=90.0) if v and len(v) == DIM]
+        except (Exception, asyncio.TimeoutError) as e:
+            logger.info("embedding checker inaktiv %s: %s", ctrl.control_id, str(e)[:80])
+            return CheckResult(present=None, source="embedding")
+        if not pvecs or not cvecs:
+            return CheckResult(present=None, source="embedding")
+        best = max((_cosine(p, c) for p in pvecs for c in cvecs), default=0.0)
+        return CheckResult(present=best >= thr, confidence=round(best, 3),
+                           source="embedding")