feat: implement strangler-fig-demo Session 1 (backend + smoke script)

Builds the four-seam, three-write-path reference demo backend: case-framework
(seam D stand-in), legacy-backend/frontend (SQL Server, seams A/B/C targets),
and new-backend (Domain/Application/Infrastructure.*/Api implementing the
source resolver, take/release-ownership, write-through translator, and owned
assessment flow), wired together via docker-compose with a plain placeholder
frontend standing in for the Angular portal until Session 2.

All 11 Architecture.Tests pass and scripts/smoke.sh passes end-to-end against
a fresh `docker compose up`, covering acceptance criteria 1-3 and 7-22.

Fixes two real domain bugs found only once the stack ran for real: the BSN
eleven-proof checksum trivially passes all-zero digits, and the adoption
mapper silently treated a partial legacy address as absent instead of failing
loudly. Also fixes several environment-specific integration issues (rootless
Podman/SELinux bind-mount permissions, a buildah NuGet layer-caching bug,
SqlClient's invariant-globalization incompatibility, and an nginx path-prefix
mismatch for the legacy frontend).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docs/adr/ADR-001-decision-independent-of-closure.md

@@ -0,0 +1,49 @@
+# ADR-001: A register decision takes effect independently of case closure
+
+## Status
+Accepted.
+
+## Context
+`case-framework` (seam D, a stand-in for a maintained vendor case-management
+framework) refuses `POST /cases/{id}/closure-request` with **409 Conflict**
+while any task on the case is still open. That rule belongs to the framework
+and is not ours to change — it is a conformist integration by design (§6).
+
+The new domain's own rule is different: once an assessment (approve/reject) is
+recorded on a `RegistrationApplication`, that decision is legally in effect
+immediately. It cannot wait for an administrative task (e.g. a filing or
+notification step) to be ticked off in a separate system.
+
+These two rules can genuinely conflict: an assessment can be recorded while a
+case-framework task is still open, at which point the case cannot yet be
+closed.
+
+## Decision
+Recording an assessment and requesting case closure are treated as two
+separate, non-transactional steps:
+
+1. `POST /api/worklist/owned/{id}/assessment` records the decision on the
+   aggregate and commits it. This always succeeds if the domain invariants are
+   satisfied, regardless of case-framework's task state.
+2. The handler then calls `POST /cases/{id}/closure-request` on seam D as a
+   best-effort follow-up. A `409` here is an **expected, non-exceptional**
+   outcome, not a failure: the assessment is not rolled back, and the response
+   reports `closurePending: true` instead of an error.
+
+The user-facing consequence: the outcome is decided immediately, with the UI
+showing `Besluit vastgelegd. Administratieve afsluiting in afwachting.` when
+closure is still pending. Administrative closure catches up whenever the
+remaining task is completed — a scenario this demo does not automate, since it
+is not a claim about the framework, only proof that it can lag safely.
+
+## Consequences
+- The domain layer's assessment-recording method must not be coupled to
+  case-framework's closure semantics — it has none of that knowledge, by
+  design (New.Domain/New.Application never reference the case-framework
+  client, see Architecture.Tests rules 1 and 8).
+- A case can sit in "decided but not administratively closed" indefinitely.
+  That is accepted, not a bug: it is the visible cost of a conformist
+  integration whose task-completion timing this system does not control.
+- No compensating transaction exists for a closure-request failure, because
+  there is nothing to compensate — the assessment was correct and complete on
+  its own terms.