Introduce enums for items, machines, and recipes, and integrate recipe selection logic. Add .gitignore and improve Flask app for query-based input handling.

.idea/pysatcalc.iml

@@ -7,4 +7,12 @@
     <orderEntry type="jdk" jdkName="uv (pysatcalc)" jdkType="Python SDK" />
     <orderEntry type="sourceFolder" forTests="false" />
   </component>
+  <component name="TemplatesService">
+    <option name="TEMPLATE_CONFIGURATION" value="Jinja2" />
+    <option name="TEMPLATE_FOLDERS">
+      <list>
+        <option value="$MODULE_DIR$/templates" />
+      </list>
+    </option>
+  </component>
 </module>