fix: double a quote in a search term, as notmuch expects

SearchTerm::quote() escaped an embedded double quote with a backslash.
notmuch has no backslash escape inside a quoted term: it doubles the
quote, and a backslash-escaped one ENDS the term. Selected text holding
a quote therefore let the rest of the selection reach the query as
syntax. Measured on a throwaway index: under a `tag:nomatch and` scope,
the backslash form of `x " or tag:inbox or id:"` matched every message,
while the doubled form matched none.

quote() now doubles the quote and leaves a backslash alone, since
notmuch reads it literally. Truncation still runs first, so a cut
cannot split a doubled pair.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/src/searchterm.h b/src/searchterm.h
index 3a0cac2..8ca67e4 100644
--- a/src/searchterm.h
+++ b/src/searchterm.h
@@ -59,8 +59,9 @@ enum class SearchMode {
 /// Quotes an arbitrary value for use as a notmuch term.
 ///
 /// Whitespace and newlines collapse to single spaces, embedded quotes are
-/// escaped, the value is capped at kMaxValueLength, and an empty or
-/// whitespace-only value yields an EMPTY STRING rather than `""`. Callers
+/// doubled (notmuch has no backslash escape), the value is capped at
+/// kMaxValueLength, and an empty or whitespace-only value yields an EMPTY
+/// STRING rather than `""`. Callers
 /// test for empty to decide whether to offer a menu entry at all.
 QString quote(const QString &value);