Rank captured tasks by what he actually said (#129)

Ordering is computed, not generated. Asking a 1.7B which of his tasks
matters most produces a fluent opinion with no basis in anything, and a
confidently wrong priority is worse than none — same posture as the
behaviour profile in internal/memory, which counts instead of summarising.

internal/tasks is a pure package (no ipc, no store, no cgo) holding the
score, the order and the Russian rendering, so the spoken list and the
/tasks page cannot drift. Four signals, all of them things he stated:
deadline (overdue > today > tomorrow > this week), stated urgency, age
with a cap so nothing rots at the bottom, and confirmed work always
ahead of mail-derived candidates. A task with no due date and no weight
scores nothing and carries no reason string — inventing a "потому что"
about a priority he never set is the failure mode this avoids.

Capture now picks up urgency he says out loud ("добавь в задачи срочно
оплатить интернет"), stripping the marker from the task text, and the web
add form offers the same three rungs. Ranking is a read: it sorts and
renders, never writes, schedules or announces.

cmd/mavweb/tasks_test.go

@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"github.com/kami/maven/internal/ipc"
+	"github.com/kami/maven/internal/tasks"
 )
 
 // fakeTaskCore serves the /tasks handler: a canned list plus a log of the
@@ -164,3 +165,61 @@ func TestHandleTasksNoCore(t *testing.T) {
 		t.Errorf("status = %d, want 503", rec.Code)
 	}
 }
+
+// The open list is ordered by the ranker, and the reason is shown so the page
+// says why a task is first instead of asking him to trust the order.
+func TestHandleTasksOrdersOpenByRank(t *testing.T) {
+	now := time.Now()
+	due := now
+	core := &fakeTaskCore{tasks: []ipc.Task{
+		{ID: 1, Text: "купить молоко", Status: "open", CreatedTs: now},
+		{ID: 2, Text: "оплатить интернет", Status: "open", CreatedTs: now, Due: &due},
+	}}
+	rec := httptest.NewRecorder()
+	handleTasks(rec, httptest.NewRequest(http.MethodGet, "/tasks", nil), core)
+	body := rec.Body.String()
+	if strings.Index(body, "оплатить интернет") > strings.Index(body, "купить молоко") {
+		t.Error("want the dated task rendered first")
+	}
+	if !strings.Contains(body, "сегодня") {
+		t.Error("want the ranker's reason shown in the why column")
+	}
+}
+
+// A candidate is ranked into place but never carries a priority reason: its due
+// date is Maven's reading of a mail, not something he stated.
+func TestHandleTasksHidesCandidateReason(t *testing.T) {
+	now := time.Now()
+	due := now
+	core := &fakeTaskCore{tasks: []ipc.Task{
+		{ID: 1, Text: "продлить страховку", Status: "candidate", CreatedTs: now, Due: &due},
+	}}
+	rec := httptest.NewRecorder()
+	handleTasks(rec, httptest.NewRequest(http.MethodGet, "/tasks", nil), core)
+	if strings.Contains(rec.Body.String(), "сегодня") {
+		t.Error("a candidate must not be shown with a priority reason")
+	}
+}
+
+func TestApplyTaskPostCarriesWeight(t *testing.T) {
+	core := &fakeTaskCore{created: true}
+	form := url.Values{"action": {"add"}, "text": {"оплатить интернет"}, "weight": {"3"}}
+	req := httptest.NewRequest(http.MethodPost, "/tasks", strings.NewReader(form.Encode()))
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	handleTasks(httptest.NewRecorder(), req, core)
+	if len(core.captured) != 1 || core.captured[0].Weight != 3 {
+		t.Fatalf("captured = %+v, want weight 3", core.captured)
+	}
+}
+
+// Out of range clamps rather than 400s; a non-number is a real client error.
+func TestApplyTaskPostClampsWeight(t *testing.T) {
+	core := &fakeTaskCore{created: true}
+	form := url.Values{"action": {"add"}, "text": {"что-то"}, "weight": {"99"}}
+	req := httptest.NewRequest(http.MethodPost, "/tasks", strings.NewReader(form.Encode()))
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	handleTasks(httptest.NewRecorder(), req, core)
+	if core.captured[0].Weight != tasks.MaxWeight {
+		t.Errorf("weight = %d, want the cap", core.captured[0].Weight)
+	}
+}