feat(flow): port flows to the chain-0.16 YAML syntax + add bytes-input variant

The earlier durchstich-gewo-14.yaml used the templated
${{ inputs.x }} syntax and rich input declarations
(type / required / description). chain 0.16 expects the
simpler $inputs.x form and flat 'inputs: { name: type }'
maps — see flows/hello.yaml in fai/chain. Rewritten to match.

Adds two siblings:

  - test-cohort.yaml: trivial stats.cohort_size-only smoke
    test. Confirms a Recl∆Im module loads, instantiates against
    the chain:platform/invoke@1.0.0 ABI, and writes a clean
    flow.completed event. Useful as the first test you run
    when wiring a fresh hub.

  - durchstich-from-file.yaml: end-to-end demo without the
    http.request permission dance. Takes the source XML as a
    bytes input (--input content=@./norm.xml), runs through
    text.akoma_normalize, stats.cohort_size and the
    system.approval gate, and writes the norm + cohort bag to
    the audit log. First end-to-end Recl∆Im flow that survives
    a hub restart with audit-trail intact.

Verified locally: chain run flows/test-cohort.yaml → flow.completed
in 5 ms; chain run flows/durchstich-from-file.yaml + approve →
flow.completed in 6 s, output bag carries normalized GewO §14
with paragraphs + source_sha256.

Signed-off-by: flemming-it <sf@flemming.it>

flows/durchstich-from-file.yaml

@@ -0,0 +1,39 @@
+# Vertikaler Durchstich, Variante "ohne http-Permission".
+#
+# Nimmt das Norm-XML als bytes-Input direkt entgegen (statt es
+# über http.request zu ziehen). Sinnvoll für den ersten end-to-
+# end-Test gegen den lokal laufenden Hub, wenn dessen Operator-
+# Policy noch keine Allowlist für gesetze-im-internet.de hat.
+#
+# Aufruf:
+#   chain run flows/durchstich-from-file.yaml \
+#     --input content=@/tmp/gewo-14-mini.xml \
+#     --input cohort_id=berlin-kmu
+
+name: durchstich-from-file
+
+inputs:
+  content: bytes
+  cohort_id: text
+
+steps:
+  - id: normalize
+    use: text.akoma_normalize@^0
+    with:
+      content: $inputs.content
+      mime: "application/xml"
+
+  - id: cohort
+    use: stats.cohort_size@^0
+    with:
+      cohort_id: $inputs.cohort_id
+
+  - id: review
+    use: system.approval@^0
+    with:
+      title: "Recl∆Im — Review GewO §14"
+      payload: $normalize.norm
+
+outputs:
+  norm: $normalize.norm
+  cohort: $cohort.cohort