feat: Journey Matcher — the delta explains the journey (Delta -> Journey, ADR-011)

The sanctioned last architectural building block. Reverses the order: not Goal -> Journey -> Delta
but Goal -> Required -> Delta -> Journey. A Journey is the EXPLANATION of the Capability Delta, not
its cause — so this is a Matcher/Explainer, not a Selector.

New module compliance/journey_matcher/ = the third independent, interchangeable function of the
pipeline, beside Company 2A (Evidence -> Capability) and RS-005 (Capability -> Delta):

  match_journeys(delta, journeys, context) -> ranked, auditable explanation

- Looks ONLY at the Capability Delta — never at certificates, regulation, tenders or the goal.
  Journey signatures are certificate-agnostic capability clusters (Input -> Output pattern).
- score = share of the delta a journey explains (recall over the missing capabilities); journey_only
  documents where a journey reaches beyond the delta so a broad journey is not silently preferred.
- Deliberately dumb + deterministic (pure set overlap; NO ML/embeddings/LLM), fully auditable
  (matched / unexplained / journey_only / context signals); a learning ranker can sit on top later.
- Signatures injected, engine hermetic. mypy --strict clean.

Validated on the real patterns (demo): a CRA+MaschinenVO delta ranks the convergence journey 100%,
"ISO27001 -> CRA" 56% (misses the machine-safety caps), "ISMS -> TISAX" 0%. This resolves the
"Scope -> Journey" jump from Customer Mission #1. Freeze exception explicitly authorised; non-runtime
-> no deploy. 12 tests pass, check-loc 0.

backend-compliance/compliance/journey_matcher/__init__.py

@@ -0,0 +1,30 @@
+"""Journey Matcher — the Delta -> Journey function of the Capability Delta Engine.
+
+The third independent function of the pipeline (after Company 2A `Evidence -> Capability` and RS-005
+`Capability -> Delta`): given ONLY the Capability Delta, rank the known journeys that best EXPLAIN it.
+A Journey is an EXPLANATION of the delta, not its cause — order is `Goal -> Required -> Delta -> Journey`.
+
+Deliberately dumb + deterministic (pure set overlap; no ML/embeddings/LLM), fully auditable, signatures
+INJECTED (certificate-agnostic capability clusters). No new corpus, no graph (freeze v1.0). The Matcher
+is sanctioned as the last architectural building block; everything after is knowledge work.
+"""
+
+from __future__ import annotations
+
+from .engine import match_journeys
+from .schemas import (
+    JourneyMatch,
+    JourneyMatchReason,
+    JourneyMatchResult,
+    JourneySignature,
+    MatchContext,
+)
+
+__all__ = [
+    "match_journeys",
+    "JourneySignature",
+    "MatchContext",
+    "JourneyMatch",
+    "JourneyMatchReason",
+    "JourneyMatchResult",
+]