Fiches de poste : message de l'organisation en bas de chaque page

Edition.volunteer_message imprimé en pied de chaque page (suite d'une
feuille comprise), la marge du bas agrandie de sa hauteur ; rien sans
message.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

backend/tests/test_position_sheets_api.py

@@ -174,3 +174,25 @@ def test_a_night_that_passes_midnight_stays_on_its_festival_day(client, edition,
     text = reader.pages[0].extract_text()
     assert "jeudi 9 juillet" in text.lower()
     assert "01:00" in text
+
+
+def test_organisation_message_is_passed_as_the_page_footer(client, edition, session, monkeypatch):
+    import app.api.position_sheets as sheets_api
+
+    captured = {}
+    original = sheets_api.generate_position_sheets_pdf
+
+    def spy(sheets, footer=None):
+        captured["footer"] = footer
+        return original(sheets, footer)
+
+    monkeypatch.setattr(sheets_api, "generate_position_sheets_pdf", spy)
+    position = make_position(session, edition)
+    make_shift(session, edition, position, start=dt_at(9, 19), end=dt_at(9, 22))
+
+    assert client.post(_url(edition), json={}).status_code == 200
+    assert captured["footer"] is None
+
+    client.patch(f"/editions/{edition.id}", json={"volunteer_message": "Repas à 18h30"})
+    assert client.post(_url(edition), json={}).status_code == 200
+    assert captured["footer"].message == "Repas à 18h30"