build the app, and ship it on Linux and Windows as well as macOS

The client itself: the sync engine and mirror, the Gmail and IMAP providers,
the screener, the three boxes and two piles, compose and send, the sanitiser
and tracker stripping, contacts, clips, backup, notifications and the guide.

The pipeline that ships it. Three runners now build in parallel and the
publish gate wants all four platform keys in latest.json before a release
leaves draft. Linux gets two more packages Tauri does not build: a flatpak
repackaged from the deb against GNOME 48, and a Nix package that relinks the
deb against nixpkgs so it runs as a native Wayland client rather than through
Xwayland. CI runs the Rust suite on all three desktops rather than on Linux
alone, and rebuilds the flatpak manifest on every push to main.

Two things that were only ever exercised on macOS and were wrong everywhere
else. The menu bar was built by adjusting the submenus macOS is given, so on
a platform whose default menu has no File or View the new File menu landed
after Edit, Check for Updates landed nowhere, and the three places and the
reading pane had no menu at all. The deb declared libwebkit2gtk-4.1-0 and
libgtk-3-0 twice, because tauri.conf.json named the dependencies Tauri
already emits.

The updater key exists now, so releases can sign their artifacts.

src-tauri/fixtures/quoted-reply-plain.eml

@@ -0,0 +1,33 @@
+Return-Path: <[email protected]>
+MIME-Version: 1.0
+Date: Wed, 2 Sep 2026 15:40:02 +0530
+Message-ID: <[email protected]>
+In-Reply-To: <[email protected]>
+References: <[email protected]>
+ <[email protected]>
+Subject: Re: Fw: (no subject)
+From: Sam Okafor <[email protected]>
+To: Priyanshu Jain <[email protected]>
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 7bit
+
+Got it, thank you. Wednesdays at five work for us.
+
+The first lesson is on the 9th, nothing to prepare. The invitation is
+attached, it should land in your calendar.
+
+Sam
+
+On Mon, 31 Aug 2026 at 09:12, Priyanshu Jain <[email protected]> wrote:
+> Hi Sam, form signed and attached. Would a weekday after school suit
+> Cooper? He finishes at four and we are ten minutes away on foot.
+>
+> On Wed, 12 Aug 2026 at 11:02, Sunny Day Music
+> <[email protected]> wrote:
+> > Enrolment received for Cooper. Term starts the week of 8 September
+> > and your teacher will be in touch to fix a weekly slot.
+> >
+> > Nothing further is needed from you today.
+>
+> Thanks,
+> Priyanshu