Replaces AgentsPage's Table-rendered roster with one AgentCard per
agent: name/status/wanted on the first line, the free-form status
message on the second (mara, scoping #4257: "main view: name, status,
message, wanted" / "message as second line" / "more like card per
agent").
Everything the old table's other columns carried (hive, matrix
link-account, config-PR link, destroy) moves into a detail panel that
opens on card click, reusing the existing Dialog modal rather than a
new docked/slideover primitive - the shared hive-side-panel drawer is a
shadow-DOM custom element swarm-ui's esbuild config can't consume yet
(same gap Dialog.tsx's own comment already flags for hive-dialog).
WantedMenu gains a showDestroy flag: the card's own menu keeps the
three everyday states, destroy gets its own button in the detail panel
instead of a fourth dropdown entry next to states someone reaches for
often.
Known regression, flagged for follow-up rather than silently dropped:
the old table's per-column sort/filter has no replacement in this view
yet.
Backend list/detail endpoint split (also requested in #4257) is
deliberately left for a follow-up PR - it's an orthogonal optimization,
not required for this interaction to work correctly against the
existing single /api/agents/status response.