feat(client): filter select_recipe by STATION_CODE with error fallback

Replace generic /api/recipes call with api_client.get_station_recipes(STATION_CODE).
Return 503 station_not_configured.html when STATION_CODE env var is unset.
Add station indicator to recipe selection page header.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

client/tests/test_measure.py

@@ -8,15 +8,18 @@ import pytest
 class TestSelectRecipe:
     """GET /measure/select tests."""
 
-    def test_select_recipe_renders(self, logged_in_client, mock_api_client):
+    def test_select_recipe_renders(self, logged_in_client, mock_api_client, monkeypatch):
         """Recipe selection page renders for MeasurementTec role."""
-        mock_api_client.get.return_value = {
-            "items": [
-                {"id": 1, "code": "REC-001", "name": "Test Recipe"},
-            ],
-            "total": 1,
-            "pages": 1,
-        }
+        monkeypatch.setenv("STATION_CODE", "ST-TEST")
+        import config
+        import importlib
+        importlib.reload(config)
+        import blueprints.measure
+        importlib.reload(blueprints.measure)
+
+        mock_api_client.get_station_recipes.return_value = [
+            {"id": 1, "code": "REC-001", "name": "Test Recipe"},
+        ]
 
         resp = logged_in_client.get("/measure/select")
         assert resp.status_code == 200