Put a session's status on its title line

[tdwd]

The sidebar card spent a third of its height on a line saying "Idle" beside a dot already saying it. The glyph moves to the title line and that row goes.

before                          after

▌ ◉ ← was here                  ▌ ● task number 2
▌ task number 2                 ▌ ⑂ session/quiet-otter-abcd
▌ ⑂ session/quiet-otter-abcd      ○ task number 1
▌ ◉ Idle                          ⑂ session/quiet-otter-abcd
  task number 1                   ◆ task number 0
  ⑂ session/quiet-otter-abcd      ⑂ session/quiet-otter-abcd
  ◉ Idle                          ✉ 2  ⊙ 3

The glyph set had to change

Idle and working were both ◉, told apart by accent against muted. That was a hint while the word sat beside it. Without the word it would have been the whole answer, and a colour is not one — a low-contrast theme flattens it, and a reader who cannot separate two hues never had it.

	before	after
working	◉	●
idle	◉	○
needs you	◆	◆
exited	◍	✕
closed	○	·

Filled is busy, hollow is quiet. Closed is a dot so it does not compete with idle, and a dead process is a cross because it is not a degree of running. TestStatusGlyphsAreDistinct pins pairwise distinctness and single-cell width — the title line budgets a fixed width for the glyph, so a two-cell one would silently eat a column of every session name.

The third line still exists, conditionally

An exit error and the mail/claim/review badges are facts about a session rather than a restatement of its dot, so they still earn a row. Most cards have none of them.

statusOf now returns a struct rather than a fourth return value — form.update grew to four and docs/architecture.md records what that cost. The new detail field carries an exit error to whichever caller has room for it.

A regression this change introduced, and caught

Moving the error out of label dropped it from the dashboard row too, where it had been shown as Exited: <err>. sessionLine now joins detail back to the label, so that view is unchanged.

Second commit

^g j/k was labelled "next / previous session". Sessions sort newest-first (store/query.go:79), so j moves down the list to an older session — "next" was the false claim, not the binding. It now says "down / up the session list". The keys are untouched: j is down, which is what every vim user expects.

Stale, and I cannot fix it

assets/deck-dashboard.png and assets/deck-codex.png show three-line cards with the old glyphs. Per CLAUDE.md those are photographed by hand against make demo, not generated, so they need a human with a terminal.