feat(filters): resolve built-in filters per account

Item 93, the Config half. Four built-in filters, Unread, Inbox, Flagged and
Sent, as generated entries in kQueryGenerators, which was already a closed set
validated on load for Sent alone.

resolvedQuery() gains an overload taking an account key, and that is what makes
a filter compose with the account dropdown instead of fighting it. A generator
is asked for the account's OWN query rather than having its all-accounts query
wrapped in a scope: wrapping gives

    path:"a/**" and (path:"a/Sent/**" or path:"b/Sent/**")

which returns the right rows only because path: is hierarchical, so a row-count
test passes against it. The tests assert on the query string for that reason,
and the mutation putting the wrap back fails two of them.

An ordinary saved query ignores the account key and keeps resolving through its
own stored account, which is the behaviour item 90 leaves alone.

matchNothingQuery() exists because an empty query means "match everything" to
notmuch: an account configuring no sent folder would otherwise give a button
labelled Sent that shows the entire Maildir.

Config gains Q_DECLARE_TR_FUNCTIONS for the filter names, which are button
labels. The generator names are not translated: they are matched against the
closed set and stored in queries.json, so translating them would make a file
written in one locale unreadable in another.

No UI yet, and no migration: the query row still builds from pinned saved
queries.

0 files changed, 0 insertions, 0 deletions