maven: calendar event querying (task 3)

Store: CalendarEvents(ctx, from, to) — filters caldav facts by key date prefix.
IPC: full wiring through interface, server dispatch, and client.
Router: ParseCalendarDate (сегодня/завтра), CalendarEventFormatter (RU reply).
Voice: calendar detection before notes RAG in IntentQuery handler.
Tests: store integration test, date parser tests, formatter tests.

Co-Authored-By: opencode <opencode@anthropic.com>

internal/ipc/client.go

@@ -277,6 +277,14 @@ func (c *Client) RecentFacts(ctx context.Context, n int) ([]Fact, error) {
 	return out, nil
 }
 
+func (c *Client) CalendarEvents(ctx context.Context, from, to time.Time) ([]Fact, error) {
+	var out []Fact
+	if err := c.call(ctx, MethodCalendarEvents, calendarEventsReq{From: from, To: to}, &out); err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
 func (c *Client) RecentNudges(ctx context.Context, n int) ([]Nudge, error) {
 	var out []Nudge
 	if err := c.call(ctx, MethodRecentNudges, nReq{N: n}, &out); err != nil {