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/e2e/test_printer_edit.py

@@ -3,6 +3,14 @@ from __future__ import annotations
 
 import pytest
 
+# The Edit button's label goes through the i18n store, which follows
+# navigator.language — on a French-locale machine it reads "Modifier", so a
+# has-text('Edit') locator only ever matched on English hosts. Target the
+# showModal() hook instead: it is the same in every language.
+# showModal(), not just edit-modal: the dialog's own close buttons reference
+# the same element id via .close().
+EDIT_BUTTON = "button[onclick*='showModal']"
+
 
 def test_printer_edit_modal_open_and_prefill(page, live_server: str, _e2e_owner_key: str) -> None:
     """Edit button opens modal with printer's current name pre-filled."""
@@ -24,8 +32,8 @@ def test_printer_edit_modal_open_and_prefill(page, live_server: str, _e2e_owner_
         )
 
     page.goto(f"{live_server}/printers", wait_until="domcontentloaded")
-    page.wait_for_selector("button:has-text('Edit')")
-    page.click("button:has-text('Edit')")
+    page.wait_for_selector(EDIT_BUTTON)
+    page.click(EDIT_BUTTON)
 
     # Dialog should be open
     page.wait_for_selector("dialog[open]")
@@ -57,7 +65,7 @@ def test_printer_edit_submit_updates_list(page, live_server: str, _e2e_owner_key
     # Find the row containing "OriginalName" and click its Edit button
     row = page.locator("tr", has=page.locator("a", has_text="OriginalName"))
     row.wait_for()
-    row.locator("button:has-text('Edit')").click()
+    row.locator(EDIT_BUTTON).click()
     page.wait_for_selector("dialog[open]")
 
     # Clear and update the name field