fix(09-01): resolve driver upload 500 and add HTMX OOB refresh path

- Import Form from fastapi for mixed multipart + form field support
- Add caller: str = Form('') parameter to upload_driver handler
- Capture new_driver from Driver.get_or_create() return tuple
- Branch on caller == 'printer_form' to emit OOB-enabled response
- Create partials/driver_upload_with_oob.html with primary driver_list
  include + hx-swap-oob select targeting id=printer-form-driver-select
- New driver is auto-selected via new_driver_id context variable

All 13 driver upload tests pass including 4 new OOB contract tests.
Full non-e2e suite: 111 passed.

imptune/api/drivers.py

@@ -6,7 +6,7 @@ import json
 import zipfile
 from pathlib import Path
 
-from fastapi import APIRouter, Request, UploadFile
+from fastapi import APIRouter, Form, Request, UploadFile
 from fastapi.responses import HTMLResponse
 from fastapi.templating import Jinja2Templates
 
@@ -33,7 +33,11 @@ def _error_response(message: str, status_code: int = 400) -> HTMLResponse:
 
 
 @router.post("/upload", response_class=HTMLResponse)
-def upload_driver(request: Request, file: UploadFile) -> HTMLResponse:
+def upload_driver(
+    request: Request,
+    file: UploadFile,
+    caller: str = Form(""),
+) -> HTMLResponse:
     """Accept a driver ZIP, parse its INF, persist via DriverStore + Peewee ORM.
 
     Returns an HTMX partial (partials/driver_list.html) on success, or an
@@ -86,7 +90,7 @@ def upload_driver(request: Request, file: UploadFile) -> HTMLResponse:
     sha256 = store.save(data)
 
     # Upsert Driver record (no duplicate if same SHA256)
-    Driver.get_or_create(
+    new_driver, _created = Driver.get_or_create(
         sha256=sha256,
         defaults={
             "original_filename": filename,
@@ -105,6 +109,19 @@ def upload_driver(request: Request, file: UploadFile) -> HTMLResponse:
         names = json.loads(d.driver_desc) if d.driver_desc else []
         driver_data.append({"driver": d, "names": names})
 
+    # When called from the printer form, emit primary fragment + OOB select refresh
+    if caller == "printer_form":
+        return templates.TemplateResponse(
+            request=request,
+            name="partials/driver_upload_with_oob.html",
+            context={
+                "driver_data": driver_data,
+                "new_driver_id": new_driver.id,
+                "parsed": parsed,
+            },
+        )
+
+    # Default: existing behavior — driver list fragment only
     return templates.TemplateResponse(
         request=request,
         name="partials/driver_list.html",

imptune/templates/partials/driver_upload_with_oob.html

@@ -0,0 +1,11 @@
+{% include "partials/driver_list.html" %}
+
+<select name="driver_id" id="printer-form-driver-select" hx-swap-oob="true">
+  <option value="">-- No driver --</option>
+  {% for item in driver_data %}
+  <option value="{{ item.driver.id }}"
+          {% if item.driver.id == new_driver_id %}selected{% endif %}>
+    {{ item.driver.original_filename }} ({{ item.names | join(', ') }})
+  </option>
+  {% endfor %}
+</select>