Improve user experience with interactive client

Based on Vue.js, mainly because it can be used without any compilation.

app/app.py

@@ -66,8 +66,28 @@ class Generator:
         return self.GENERATED_STL_FILE_NAME
 
 
-@app.route("/generate/<name>")
-async def generate_rest(name: str):
+@app.route("/generate", methods=["POST"])
+async def generate():
+    try:
+        # support both modern JSON body requests as well as classic forms
+        form_data = await request.form
+        json_data = await request.json
+
+        if form_data:
+            data = form_data
+
+        elif json_data:
+            data = json_data
+
+        else:
+            raise ValueError
+
+        name = data["name"]
+
+    except (TypeError, KeyError, ValueError):
+        abort(400)
+        return
+
     async with semaphore:
         with tempfile.TemporaryDirectory(prefix="fablab-bottle-clip-generator-") as tempdir:
             generator = Generator(name, tempdir)
@@ -98,24 +118,17 @@ async def generate_rest(name: str):
 
             # using secure_filename allows us to send the file to the user with some safe yet reasonably
             # identifiable filename
-            return await send_file(
+            response = await send_file(
                 bytes_io,
                 mimetype="model/stl",
                 as_attachment=True,
                 attachment_filename=out_filename,
             )
 
+            # avoid the need for a content-disposition parser in the client code
+            response.headers["download-filename"] = out_filename
 
-# aside from the RESTful API above, we need a "traditional" HTML forms compatible end point
-@app.route("/generate")
-async def generate_form():
-    try:
-        name = request.args["name"]
-    except KeyError:
-        abort(400)
-        return
-
-    return await generate_rest(name)
+            return response
 
 
 @app.route("/")