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/widgets/delta_mark.dart

@@ -0,0 +1,98 @@
+import 'dart:math' as math;
+
+import 'package:flutter/material.dart';
+
+import '../theme/lawheatmap_tokens.dart';
+
+/// The F∆I / Ch∆In brand mark: an upward triangle (the `∆`) with
+/// a petrol "eye" at the centre. Geometry mirrors fai_web's
+/// Logo.astro — the triangle IS the "A"; the eye-dot IS the dot
+/// of the "i".
+///
+/// Subtle 9s breathing pulse on the eye (matches fai_web's
+/// `.eye-pulse`). Set [animated] to false for static contexts
+/// (icons, screenshots).
+class DeltaMark extends StatefulWidget {
+  const DeltaMark({super.key, this.size = 64, this.animated = true});
+
+  final double size;
+  final bool animated;
+
+  @override
+  State<DeltaMark> createState() => _DeltaMarkState();
+}
+
+class _DeltaMarkState extends State<DeltaMark>
+    with SingleTickerProviderStateMixin {
+  late final AnimationController _controller;
+
+  @override
+  void initState() {
+    super.initState();
+    _controller = AnimationController(
+      vsync: this,
+      duration: const Duration(seconds: 9),
+    );
+    if (widget.animated) {
+      _controller.repeat();
+    }
+  }
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return AnimatedBuilder(
+      animation: _controller,
+      builder: (context, _) {
+        final t = _controller.value;
+        // Breathe: scale 1 → 1.28 → 1 over the cycle.
+        final pulse = 1.0 + 0.28 * (1 - (math.cos(t * 2 * math.pi).abs()));
+        return CustomPaint(
+          size: Size.square(widget.size),
+          painter: _DeltaPainter(pulse: widget.animated ? pulse : 1.0),
+        );
+      },
+    );
+  }
+}
+
+class _DeltaPainter extends CustomPainter {
+  _DeltaPainter({required this.pulse});
+
+  final double pulse;
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    final w = size.width;
+    final h = size.height;
+
+    // Upward triangle, geometric centre.
+    final stroke = Paint()
+      ..color = const Color(0xFFE9E7E2)
+      ..style = PaintingStyle.stroke
+      ..strokeWidth = w * 0.04
+      ..strokeJoin = StrokeJoin.miter;
+
+    final inset = w * 0.08;
+    final tri = Path()
+      ..moveTo(w / 2, inset)
+      ..lineTo(w - inset, h - inset)
+      ..lineTo(inset, h - inset)
+      ..close();
+    canvas.drawPath(tri, stroke);
+
+    // Eye — petrol fill, centred on the triangle's centroid.
+    final eyeCentre = Offset(w / 2, inset + (h - 2 * inset) * 2 / 3);
+    final eyeR = w * 0.06 * pulse;
+    final eye = Paint()..color = LawHeatmapColors.signal;
+    canvas.drawCircle(eyeCentre, eyeR, eye);
+  }
+
+  @override
+  bool shouldRepaint(covariant _DeltaPainter old) => old.pulse != pulse;
+}