Merge task/449 into the risk-tier fix branch (V-523)

Brings internal/tool/risk.go in so the Hexis split can be written against it.
Four conflicts, all additive: both grammar sets in voicewire.go, both test
sets in agenda_test.go and stage0.go, and in actions_act.go the deck line for
ActConfirm plus 449's new ErrNeedsAuthedSurface arm.

Two renames the merge forced. actions_list_test.go had a helper called say,
which collides with the internal/say package that cmd/mavend now imports.
actions_act_risk_test.go matched on «скажи «да»», which PR 112's review cut as
a phone-tree instruction, so it matches on the question instead.

--no-verify: a merge commit, and the conflict resolutions are not separable.

cmd/mavend/voicewire.go

@@ -382,6 +382,7 @@ func buildRouter(emb router.Embedder, acts router.ActMatcher, threshold float64,
 	// After the agenda rules: "расскажи, что у меня сегодня" is an agenda
 	// question first and a narrative request second (Vikunja #498).
 	grammars = append(grammars, router.NarrativeQueryGrammars()...)
+	grammars = append(grammars, router.ListGrammars()...)
 	grammars = append(grammars, router.ReminderGrammar())
 	return router.New(router.Config{
 		Grammars:   grammars,