feat: memory-only sessions on HTTP, streamed exports, UI refresh

Session

- COOKIE_SECURE=false no longer persists the owner key for ten years.
  services/session.cookie_kwargs() drops max_age in that mode, so the
  browser holds the key in memory and the session ends with the window.
  Everything still persists server-side; only the browser link is
  temporary. base.html shows a warning banner (FR/EN) and an extra
  paragraph in the onboarding modal, and the README explains the
  trade-off and the backup-key escape hatch.
- Both cookie writers (middleware, POST /session/restore) go through
  cookie_kwargs() so the policy cannot drift between them.
- The CSRF guard on /session/restore compared request.url.scheme against
  the Origin header. Behind a TLS-terminating proxy uvicorn sees http
  while the browser sends https, so every legitimate restore was
  rejected with 403. It now compares hosts only, including
  X-Forwarded-Host.
- /static/*, /favicon.ico and /robots.txt skip the middleware. Each
  cookieless hit was inserting an Owner row no browser could ever use.

Reliability

- Malformed printer-form FK fields no longer escape as HTTP 500:
  a non-numeric client_id/driver_id raised ValueError and an unknown
  driver_id hit a FOREIGN KEY constraint. Both are now 400/404 HTMX
  fragments, and the duplicated field checks moved into
  _validate_fields().
- Package exports stream. build_intunewin() encrypts the inner ZIP in
  1 MB chunks against temp files with a streaming HMAC and SHA256, and
  both endpoints serve the result with FileResponse plus a background
  cleanup task. A 100 MB driver used to be held in memory three or four
  times over per concurrent download. The byte layout is unchanged.
- FileResponse also escapes the download filename, which was previously
  interpolated raw into Content-Disposition.
- python-multipart >= 0.0.18 (CVE-2024-53981, reachable from
  /drivers/upload) and Pillow >= 10.3 (CVE-2024-28219, reachable from
  icon upload).
- icons.py reads cfg.ICONS_DIR instead of re-deriving the path from
  DATA_DIR, matching the .intunewin export.

UI

- Sidebar/topbar shell, inline SVG icon macros (partials/icons.html),
  card and data-table components, grouped printer list, and the
  dedicated /printers/new page replacing partials/printer_form.html.

Tests

- 194 pass with a bare `pytest tests/`: tests/conftest.py now forces
  cfg.COOKIE_SECURE = False like the e2e conftest already did, so the
  Secure cookie is no longer dropped over http://testserver.
- New coverage for the malformed-FK guards, the chunk-boundary cases in
  the encrypt loop (every residue mod _CHUNK plus a multi-megabyte
  payload), temp-dir cleanup after both exports, and the whole
  COOKIE_SECURE matrix.
- test_printer_edit.py located the Edit button by its translated label,
  so it only passed on English-locale machines. It now targets the
  showModal() hook, which also cuts the e2e run from 84s to 15s.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tests/test_printer_crud.py

@@ -392,3 +392,91 @@ def test_client_links_in_printer_list(client: TestClient, owner) -> None:
     resp = client.get("/printers")
     assert resp.status_code == 200
     assert f'href="/clients/{cl.id}"' in resp.text
+
+
+# ---------------------------------------------------------------------------
+# Malformed FK form fields — these used to escape as HTTP 500
+# ---------------------------------------------------------------------------
+
+
+def test_create_rejects_non_numeric_client_id(client: TestClient, owner) -> None:
+    """A non-numeric client_id is a 400 fragment, not a ValueError traceback."""
+    resp = client.post(
+        "/printers",
+        data={
+            "name": "Bad FK",
+            "ip_address": "10.0.5.1",
+            "port_name": "IP_10_0_5_1",
+            "client_id": "abc",
+        },
+        follow_redirects=False,
+    )
+    assert resp.status_code == 400
+    assert "Invalid client id" in resp.text
+
+
+def test_create_rejects_non_numeric_driver_id(client: TestClient, owner) -> None:
+    resp = client.post(
+        "/printers",
+        data={
+            "name": "Bad FK",
+            "ip_address": "10.0.5.2",
+            "port_name": "IP_10_0_5_2",
+            "driver_id": "not-an-id",
+        },
+        follow_redirects=False,
+    )
+    assert resp.status_code == 400
+    assert "Invalid driver id" in resp.text
+
+
+def test_create_rejects_unknown_driver_id(client: TestClient, owner) -> None:
+    """An unknown driver id is a 404 fragment, not a FOREIGN KEY IntegrityError."""
+    resp = client.post(
+        "/printers",
+        data={
+            "name": "Ghost Driver",
+            "ip_address": "10.0.5.3",
+            "port_name": "IP_10_0_5_3",
+            "driver_id": "9999",
+        },
+        follow_redirects=False,
+    )
+    assert resp.status_code == 404
+    assert "Driver 9999 not found" in resp.text
+
+
+def test_update_rejects_unknown_driver_id(client: TestClient, owner) -> None:
+    from imptune.db.models import Printer
+
+    printer = Printer.create(
+        name="Patch Me",
+        ip_address="10.0.5.4",
+        port_name="IP_10_0_5_4",
+        owner=owner,
+    )
+    resp = client.patch(
+        f"/printers/{printer.id}",
+        data={"name": "Patch Me", "driver_id": "9999"},
+    )
+    assert resp.status_code == 404
+    assert "Driver 9999 not found" in resp.text
+    # The printer must be untouched
+    assert Printer.get_by_id(printer.id).driver is None
+
+
+def test_update_rejects_non_numeric_driver_id(client: TestClient, owner) -> None:
+    from imptune.db.models import Printer
+
+    printer = Printer.create(
+        name="Patch Me Too",
+        ip_address="10.0.5.5",
+        port_name="IP_10_0_5_5",
+        owner=owner,
+    )
+    resp = client.patch(
+        f"/printers/{printer.id}",
+        data={"name": "Patch Me Too", "driver_id": "??"},
+    )
+    assert resp.status_code == 400
+    assert "Invalid driver id" in resp.text