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.html

@@ -9,6 +9,11 @@
 <input type=hidden name=action value=add>
 <input type=text name=text placeholder="что нужно сделать" size=44 required>
 <input type=date name=due title="due date (optional)">
+<select name=weight title="importance (optional)">
+<option value=0>normal</option>
+<option value=2>важно</option>
+<option value=3>срочно</option>
+</select>
 <button class=btn>add</button>
 </form>
 </section>
@@ -38,10 +43,12 @@
 
 <section class=card>
 <h2 class=card-title>open <span class=badge>{{len .Open}}</span></h2>
+<div class=hint>most pressing first — by the deadlines and the urgency you gave, nothing guessed.</div>
 {{if .Open}}<div class=scroll><table>
-<tr><th>task</th><th>from</th><th>due</th><th>captured</th><th></th><th></th></tr>
+<tr><th>task</th><th>why</th><th>from</th><th>due</th><th>captured</th><th></th><th></th></tr>
 {{range .Open}}<tr>
 <td class=text-max>{{.Text}}</td>
+<td class=hint>{{.Why}}</td>
 <td class=hint>{{.Source}}</td>
 <td>{{.Due}}</td>
 <td class=muted>{{.Created}}</td>