feat(ui): let the user choose newest or oldest first

Two entries, straight to notmuch. This adds a feature rather than replacing one:
the column header was decorative and nothing implemented click-to-sort, so
removing the header with the grid lost nothing.

Stored in uistate.conf, never in the hand-edited config, and range-guarded on
read: a stale file can hold anything, which is the lesson item 58 recorded.

SortOrder needed qRegisterMetaType despite carrying Q_ENUM. Q_ENUM gives the
enum a meta-object entry, not a metatype registered under the name invokeMethod
resolves, so the queued runQuery would have dropped its sort argument at runtime
and every query would have silently run newest-first. Nothing in the suite
exercises a real worker thread, so this was asserted directly rather than left
to a warning nobody would see. It is registered beside the type rather than in
MainWindow's constructor: a first attempt put it there and passed only because
the test that catches it never constructs a MainWindow.

The account dropdown's entries now carry their account's colour as a swatch,
which is what makes the accent bar on a card mean anything: a colour down a
card's edge says nothing until something maps it to a name. Raw colour here
rather than the blended line colour, since a swatch is a filled patch like a
chip rather than a thin line. Its test builds its own two-account config: reading
the environment's made it SKIP wherever no accounts are configured, which is a
test that asserts nothing while reporting success.

1 files changed, 16 insertions, 0 deletions

diff --git a/src/notmuchworker.cpp b/src/notmuchworker.cpp
index a6b0a29..d34c032 100644
--- a/src/notmuchworker.cpp
+++ b/src/notmuchworker.cpp
@@ -119,9 +119,25 @@ void walkReplies(notmuch_messages_t *messages, int depth,
 
 } // namespace
 
+/// Registers SortOrder for queued calls, once, before main() runs.
+///
+/// Q_ENUM alone is NOT enough for a queued Q_ARG: it gives the enum a
+/// meta-object entry, not a metatype registered under the name invokeMethod
+/// resolves, so MainWindow's queued runQuery would drop its sort argument at
+/// runtime with a warning and every query would silently run newest-first.
+///
+/// Here rather than in MainWindow's constructor, because the registration
+/// belongs to the type rather than to one consumer: a caller that never
+/// constructs a MainWindow (a test, or a future headless mode) needs it too,
+/// and that is exactly how the first attempt at this passed by accident and
+/// failed under test.
+static const int kSortOrderMetaType =
+    qRegisterMetaType<NotmuchWorker::SortOrder>("NotmuchWorker::SortOrder");
+
 NotmuchWorker::NotmuchWorker(const QString &notmuchConfigPath, QObject *parent)
     : QObject(parent), m_configPath(notmuchConfigPath)
 {
+    Q_UNUSED(kSortOrderMetaType);
 }
 
 NotmuchWorker::~NotmuchWorker()