feat: load the contact store once and feed both consumers

MainWindow reads contactsDir() once while building its UI, holds the
result in m_contacts, and hands it to the query bar's completer right
after that is constructed and to every ComposeWindow as it opens. An
empty contactsDir() skips the call, so a machine with no address book
pays nothing and warns about nothing.

The directory is not watched: a restart picks up a vdirsyncer update,
and a QFileSystemWatcher would be a live-index feature nobody asked for.

No action is added, so none of the five places in "Adding an action is
FIVE places" applies: there is no name in KeyMap::knownActions(), no
default binding, no icon-table entry and no menu entry to add.

0 files changed, 0 insertions, 0 deletions