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

internal/router/task_test.go

@@ -0,0 +1,60 @@
+package router
+
+import "testing"
+
+func TestParseTaskCapture(t *testing.T) {
+	cases := []struct {
+		in   string
+		text string
+		ok   bool
+	}{
+		{"добавь в задачи купить молоко", "купить молоко", true},
+		{"Добавь в список дел: позвонить в банк", "позвонить в банк", true},
+		{"запиши задачу починить кран.", "починить кран", true},
+		{"новая задача — оплатить интернет", "оплатить интернет", true},
+		{"add a task buy milk", "buy milk", true},
+		// A marker with nothing after it files nothing.
+		{"добавь в задачи", "", false},
+		{"новая задача", "", false},
+		// Not a capture: he is talking, not filing.
+		{"надо бы поспать", "", false},
+		{"я не добавил молоко в список", "", false},
+		{"какие у меня задачи?", "", false},
+		{"", "", false},
+	}
+	for _, c := range cases {
+		text, ok := ParseTaskCapture(c.in)
+		if ok != c.ok || text != c.text {
+			t.Errorf("ParseTaskCapture(%q) = (%q, %v), want (%q, %v)", c.in, text, ok, c.text, c.ok)
+		}
+	}
+}
+
+func TestIsTaskListQuery(t *testing.T) {
+	yes := []string{
+		"какие у меня задачи?",
+		"что мне нужно сделать?",
+		"покажи список дел",
+		"сколько у меня задач?",
+		"задачи",
+		"мои задачи",
+		"what should I do",
+	}
+	for _, s := range yes {
+		if !IsTaskListQuery(s) {
+			t.Errorf("IsTaskListQuery(%q) = false, want true", s)
+		}
+	}
+	no := []string{
+		"как дела?",
+		"какая погода?",
+		"напомни мне позвонить маме в шесть",
+		"я сделал зарядку",
+		"",
+	}
+	for _, s := range no {
+		if IsTaskListQuery(s) {
+			t.Errorf("IsTaskListQuery(%q) = true, want false", s)
+		}
+	}
+}