Merge branch 'feature/qaction-menus'

Menus, a toolbar and a generated shortcut reference, built on converting
the action registry from a hash of callbacks to QActions. Along the way:
three default key bindings that had never fired, a shortcut dialog taller
than the screen, thread list columns that could not be resized, no visible
feedback that a tag action had landed, and a tags column so wide it was
unreadable.

Backlog items 3, 8, 9, 13 and 14 done; 11 partly.

1 files changed, 62 insertions, 0 deletions

diff --git a/src/tagchip.h b/src/tagchip.h
new file mode 100644
index 0000000..9bd4e78
--- /dev/null
+++ b/src/tagchip.h
@@ -0,0 +1,62 @@
+/*
+ * qtmaildir - a Qt6 mail client for notmuch-indexed Maildirs
+ * Copyright (C) 2026 Danilo M. <danix@danix.xyz>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#pragma once
+
+#include <QColor>
+#include <QRect>
+#include <QSize>
+#include <QString>
+#include <QStyledItemDelegate>
+
+class QPainter;
+class QFontMetrics;
+
+/// Draws one rounded, filled tag chip. Shared so the account chip in the
+/// thread list and the strip under the message pane cannot drift apart.
+namespace TagChip {
+
+/// Padding inside a chip and the gap between two of them.
+constexpr int kPaddingX = 6;
+constexpr int kPaddingY = 1;
+constexpr int kSpacing = 4;
+constexpr int kRadius = 3;
+
+QSize sizeFor(const QFontMetrics &metrics, const QString &text);
+
+/// Paints the chip into `rect`, using `text` and `background`. The text colour
+/// is derived from the fill so it stays legible.
+void paint(QPainter *painter, const QRect &rect, const QString &text,
+           const QColor &background);
+
+}  // namespace TagChip
+
+/// Item delegate for the subject column: draws the account chip in front of
+/// the subject text, so which mailbox a thread came from reads at a glance
+/// without a tags column spelling it out.
+class SubjectDelegate : public QStyledItemDelegate
+{
+    Q_OBJECT
+public:
+    using QStyledItemDelegate::QStyledItemDelegate;
+
+    void paint(QPainter *painter, const QStyleOptionViewItem &option,
+               const QModelIndex &index) const override;
+    QSize sizeHint(const QStyleOptionViewItem &option,
+                   const QModelIndex &index) const override;
+};