Close sessions from panes + review/answer plans in the reader

[lacraig2]

Three related cockpit asks. Builds on the current round-5-cockpit working tree
(the first commit is a snapshot of in-progress local changes, per request).

1. Prominent close (✕) on task rows — feat(panes)

Closing a session was only reachable from the row's ⋯ menu (a buried danger
row) and, in the open-pane deck, from a desktop-only menu — so on a phone
there was no accessible way to close a session. Adds an always-visible ✕ on
each task row that opens the existing confirm dialog (RemoveDialog): one tap to
reach, still gated so it's never destructive by accident.

2. Answer questions without leaving the reader — feat(viewer)

Permission menus and AskUserQuestion / ExitPlanMode prompts are terminal
overlays; in reader (conversation) mode they were invisible or buried inside a
collapsed "N steps" tool run, forcing a switch to the terminal to answer.

• ExitPlanMode now renders as the plan itself — markdown inline, expanded
  by default in the reader, collapsible.
• AskUserQuestion renders as its question + choices inline.
• Both are excluded from tool-run grouping so they always stand alone.

3. Review plans where you answer them — feat(options)

ExitPlanMode plans were reduced to a one-line prompt, so a plan could only be
read in the raw terminal (usually too long to scroll there). The full plan body
now rides through ParsedMenu.detail → PendingOptions.detail and renders in
OptionPicker as a scrollable, expandable block right above the choices — so the
plan is reviewable exactly where it's answered, in both the drive cockpit and the
panes reader. The plan body is folded into the selection fingerprint so a
re-issued plan can't be answered from a stale view.

Tests

• Backend: 424 passed (adds plan-detail + fingerprint coverage in test_options.py).
• Frontend: 102 passed (adds OptionPicker, inline plan/question render, TaskRow
  close, and tool-run exclusion tests).

Note on the base

The branch's first commit snapshots uncommitted local work that was already on
round-5-cockpit; the three feat(...) commits are the actual change. When you
commit your own WIP, reconcile as needed.