feat: initial F∆I Law-Heatmap Phase 0 scaffold

First end-to-end-buildable cut of the pflicht-/graph-basierte
Wirkungsanalyse von Rechtsnormen, running on Ch∆In. Demo runs
without external dependencies and without a hub connection so
the methodology + UI stack can be reviewed before any Verbands-
Kooperation or Beirats-Validierung kicks in.

Tree layout

  MACHBARKEITSSTUDIE.md       v0.3 — pflicht-basierte Methodik,
                              4-Tier-Evidenz, 8 law*-Module
                              auf Ch∆In statt der alten F∆I-
                              Plattform.
  RUN.md                      one-page how-to-run.
  flows/durchstich-gewo-14.yaml
                              vertical Phase-0 flow: pull →
                              normalize → duties → citations →
                              cohort → skm → frust → benefit →
                              attribution → system.approval.
  app/                        Flutter macOS client, design
                              language pulled from fai_web
                              (ink #08090A, paper #F4F3EF,
                              petrol signal #2E8F9E). Mock
                              repository ships five fixture
                              norms with real source URLs and a
                              permanent T4 demo-banner so no
                              figure can be mistaken for a
                              validated one.

Module repos (separate, see chain-modules*/):

  text-akoma-normalize, text-deontic-extract, graph-citation-
  extract, text-readability-score, stats-cohort-size, graph-
  shapley-attribution, econ-skm-score, law-benefit-score.

What runs today

  - flutter analyze: 0 issues
  - flutter test: 2/2 (landing + nav-to-shell smoke)
  - flutter build macos (via app/build-macos.sh) and ad-hoc
    codesign, app launches and the Dart VM service comes up
  - native cargo test green on every module
  - cargo build --release --target wasm32-wasip2 produces a
    130 KiB artefact for text-akoma-normalize

What is deliberately mock / stub

  - gRPC wire from the client to a chain serve hub (Repository
    abstraction is in place; live impl is the next step)
  - NKR Bürokratiekosten-Datenbank ingestion (for the canonical
    h-Werte that close out the Engpass per Studie §6.7)
  - DESTATIS GENESIS-API adapter for stats.cohort_size

License: Apache-2.0. Author/contact in MACHBARKEITSSTUDIE.md.
Signed-off-by: flemming-it <sf@flemming.it>

app/lib/data/models.dart

@@ -0,0 +1,144 @@
+// Domain model for the F∆I Law-Heatmap client.
+//
+// These types are the lingua franca between the (eventually
+// gRPC-fed) repository and the UI. Names mirror the Studie's
+// §5.3 data model.
+
+/// Evidence tier of the lowest-tier ingredient in a value.
+/// Per Studie §6.7: "Regel der niedrigsten Stufe" — any composed
+/// figure carries the tier of its weakest input.
+enum EvidenceTier {
+  /// Official / peer-reviewed: NKR, DESTATIS, ifo, ZEW.
+  t1,
+
+  /// Verbands-Erhebung: DIHK, BDI, ZDH, IHK.
+  t2,
+
+  /// Eigene strukturierte Erhebung (Phase 2/3).
+  t3,
+
+  /// Qualitatives Signal — pain indicator only, never magnitude.
+  t4,
+}
+
+extension EvidenceTierLabel on EvidenceTier {
+  String get short => switch (this) {
+        EvidenceTier.t1 => 'T1',
+        EvidenceTier.t2 => 'T2',
+        EvidenceTier.t3 => 'T3',
+        EvidenceTier.t4 => 'T4',
+      };
+
+  String get description => switch (this) {
+        EvidenceTier.t1 => 'amtlich / peer-reviewed',
+        EvidenceTier.t2 => 'Verband',
+        EvidenceTier.t3 => 'eigene Erhebung',
+        EvidenceTier.t4 => 'qualitatives Signal',
+      };
+}
+
+/// A citable source — never an LLM, always a public document or
+/// dataset reference. UI surfaces these next to every figure.
+class Source {
+  const Source({
+    required this.label,
+    required this.url,
+    required this.tier,
+    this.note,
+  });
+
+  final String label;
+  final String url;
+  final EvidenceTier tier;
+  final String? note;
+}
+
+/// One atomic obligation (Pflicht) extracted from a norm.
+/// Tuple shape matches Studie §6.3.
+class Duty {
+  const Duty({
+    required this.modality,
+    required this.addressee,
+    required this.action,
+    required this.frequency,
+    required this.sourceNorm,
+    this.authority,
+    this.consequence,
+  });
+
+  final String modality; // OBLIGATION | PROHIBITION | …
+  final String addressee;
+  final String action;
+  final String frequency;
+  final String sourceNorm;
+  final String? authority;
+  final String? consequence;
+}
+
+/// One norm version — a versioned legal text identified by its
+/// (synthetic for now) ELI/CELEX.
+class Norm {
+  const Norm({
+    required this.eli,
+    required this.title,
+    required this.jurabk,
+    required this.paragraph,
+    required this.standDate,
+    required this.sourceUrl,
+    required this.sourceSha256,
+  });
+
+  final String eli;
+  final String title;
+  final String jurabk;
+  final String paragraph;
+  final DateTime standDate;
+  final String sourceUrl;
+  final String sourceSha256;
+}
+
+/// A heatmap point: one norm with its computed scores.
+/// Axes mirror §6 in the study.
+class Evaluation {
+  const Evaluation({
+    required this.norm,
+    required this.skmEurPerYear,
+    required this.benefitScore,
+    required this.affectedCount,
+    required this.frustScore,
+    required this.tierLowest,
+    required this.duties,
+    required this.sources,
+    required this.auditEventId,
+    this.notes,
+  });
+
+  final Norm norm;
+
+  /// Yearly bureaucracy cost across the addressee population.
+  /// €/year, computed via SKM (`P × F × T × h`).
+  final double skmEurPerYear;
+
+  /// 0–5, composite of seven dimensions
+  /// (safety / market / legal-certainty / EU-harmony / …).
+  final double benefitScore;
+
+  /// Number of addressees (KMU, Bürger, etc.). UI uses this for
+  /// heatmap point size.
+  final int affectedCount;
+
+  /// 0–10, composite of readability + Verweistiefe + Akteurs-
+  /// pluralität + Norm-Volatilität.
+  final double frustScore;
+
+  /// Lowest tier among all ingredients of any displayed figure.
+  final EvidenceTier tierLowest;
+
+  final List<Duty> duties;
+  final List<Source> sources;
+
+  /// Pointer into the Ch∆In audit log (SQLite event_log row).
+  final String auditEventId;
+
+  final String? notes;
+}