Refactor transport calculation into shared domain

app.py

@@ -33,6 +33,7 @@ from pdf_report import (
     safe_report_filename,
 )
 from roll_calculation import calculate_roll, modify_calculation
+from transport_calculation import analyze_transport, transport_presets
 
 app = Flask(__name__)
 auth = HTTPBasicAuth()
@@ -155,7 +156,11 @@ def log_access(username, endpoint, method, status=200):
 def index():
     """Main calculator page - requires authentication"""
     log_access(auth.current_user(), "/", "GET")
-    return render_template("roll_calculator.html", core_presets=CORE_PRESETS)
+    return render_template(
+        "roll_calculator.html",
+        core_presets=CORE_PRESETS,
+        transport_presets=transport_presets(),
+    )
 
 
 @app.route("/static/<path:filename>", methods=["GET"])
@@ -212,6 +217,15 @@ def modify_roll_calculation():
     return jsonify(result), 200
 
 
+@app.route("/api/calculations/transport", methods=["POST"])
+@auth.login_required
+def create_transport_calculation():
+    """Execute the shared transport-capacity calculation."""
+    result = analyze_transport(request.get_json(silent=True))
+    log_access(auth.current_user(), "/api/calculations/transport", "POST")
+    return jsonify(result), 200
+
+
 def _create_pdf(calculation_request):
     result = calculate_roll(calculation_request, build_info=BUILD_INFO)
     report = report_from_calculation_result(result)