Capture tasks, with one intake seam mail can call later (#130)

A task is not a fact and not a note. A fact is a claim about the world that a
correction supersedes; a note is something to recall by meaning. A task is work
with a lifecycle, and the read that matters is "everything outstanding right
now" — which over an append-only log would mean replaying history on every
question. So: a tasks table, migration #14, statuses candidate/open/done/dropped
that each move forward exactly once.

Dedupe is on normalised text among LIVE rows only, via a partial unique index.
That is the property the mail side needs: an extractor may call CaptureTask for
every message it reads, as often as it likes, without growing the list — while a
weekly errand is still capturable again once the last one is done.

Three ways in, one seam. ipc.CaptureTaskReq is it: the voice path
(router.ParseTaskCapture on an explicit marker — "добавь в задачи …", never
"надо бы поспать"), the /tasks form, and the email reader from #246 when it
exists. Mail-derived items set Source "email:<account>", Status "candidate" and
Evidence to whatever makes the row reviewable; a candidate is inert until he
confirms it on /tasks, and Maven names it as unconfirmed when she recites the
list rather than putting words in his mouth.

No new intent — the router enum is a contract with the relabelling prompt, so
capture rides the note intent and the list rides a query source, both matched
deterministically like the calendar and plan matchers already are.

Nothing here speaks. No tick rule reads tasks; the list is answered when asked
about, which is why /tasks POST is not step-up gated the way /tools and
/routines are — a task write moves no boundary.

Vikunja #130

cmd/mavend/actions_note.go

@@ -11,6 +11,12 @@ import (
 // actionNote handles router.IntentNote: embed the note, persist it, and
 // index it for recall.
 func (h *reactiveHandler) actionNote(ctx context.Context, dec router.Decision) string {
+	// An utterance that explicitly files a task is work, not recall, and
+	// belongs in the task store (Vikunja #130). Checked before the embedding
+	// is paid for. Everything else is a note, exactly as before.
+	if reply, ok := h.captureTaskFromNote(ctx, dec); ok {
+		return reply
+	}
 	// embed the note text with the same model the classifier uses, persist
 	// via CoreAPI (source=tap:voice). Semantic recall lives in `notes`, not
 	// facts — no predicate reads it (spec's two-memory split).