Release 1.1.0

Version bump, the README line about units, and two new manual checks in the release checklist (export then New invoice
through the real save dialog, and units).

Claude-Session: https://claude.ai/code/session_01PZypiWDfMkDTeEPeXjRhW5

docs/RELEASE.md

@@ -71,6 +71,11 @@ Linux and Windows. Windows has never been run on real hardware, so treat it as u
 - **Template picker.** Open all 14 templates; switch A4 and Letter and the margin presets; check the logo slots.
 - **Export.** Issue an invoice; export searchable and flattened; change settings and re-export; "Original as issued"
   must be byte-identical to the archived PDF. On Windows, check file names with `/`, `:` and reserved names.
+- **Export, then New invoice.** Issue and export in both formats through the real save dialog, press "New invoice",
+  issue and export a second one. The window must stay usable after every export (1.1.0 fixed a blank window caused
+  by buttons inside a Carbon notification; the dialog itself can only be checked by hand).
+- **Units.** Add a rate line in hours typed as `4:30` (amount counts 4.5), one in km and one with a custom unit;
+  check the quantity and rate columns on a few templates and A4/Letter.
 - **Fonts.** Settings, Fonts: import a TTF for Now, Gotham or Open Sauce One (if a licensed file is at hand), confirm
   a template that uses it changes, remove it again.
 - **Clients.** Create a client with structured address and GST category; use it on an invoice.