[BUG] Agent view has no "needs input, sleeping" indicator — the alive/sleeping distinction exists for done sessions but not for blocked ones

The list encodes two things at once, and it does it well for most states: the colour carries the session's state, and the shape carries whether it is alive — an asterisk for a live session, a dot for a sleeping one. So a finished session that is still loaded shows a green asterisk, and a finished session that has gone to sleep shows a green dot. That is genuinely useful and I rely on it.

The problem is that the shape distinction was never extended to "needs input". There is a yellow asterisk and there is no yellow or orange dot. So both of these render identically:

• a session that is live right now and waiting on my answer;
• a session that asked something and then went to sleep.

Observed matrix:

                alive (asterisk)      sleeping (dot)
  working       grey, animating       —
  done          green asterisk        green dot
  needs input   yellow asterisk       MISSING

What I expected. A yellow or orange dot for "needs input, but the session is closed". That one cell completes the table, and the whole list becomes readable at a glance.

Why it matters. I run a fleet of long-lived parallel sessions, each owning a piece of work, and they hand context to one another with cross-session messaging. A sleeping session cannot receive a message, so before sending anything I need to know which are alive. The list can tell me that for every state except the one I care about — and the sessions that have been idle longest, the ones most likely to be running on a stale picture, are exactly the ones it cannot flag.

Note on documentation. I could not find the indicator legend documented anywhere; docs/en/agents-view returns 404. The matrix above is from observation, so if the intended meanings differ from what I describe, that is worth correcting — but the outcome I am reporting is the same either way: two different situations share one indicator.

Version. 2.1.228, macOS.

Related: #83554 (the view buckets on state while prompt-state lives in tempo) and #77804 (background sessions awaiting AskUserQuestion show as "working"). My own #75663 concerns the same warm/cold transition in the agent switcher.