v0.2.0

A major dashboard and fleet release. Fleet now keeps one persistent, self-healing
SSH connection per host; the Overview is a responsive, customisable multi-column
grid with eight panels and richer metrics (per-core CPU, swap, inodes,
connections, failed services, kernel/OS); the tui toolkit gained reusable,
extractable widgets; and a ? help overlay plus fleet drill-in round out the UX.

Changed

• Responsive Overview — the Overview now flows its panels into one, two, or
  three columns depending on terminal width (≥105 cols → two, ≥160 → three),
  filling the width with a divider between columns, laid out as an ordered grid
  (row-major, honouring your panel order), and using width up to 200 cols instead
  of the old 100-col cap. Customised layouts keep the multi-column rendering
  (previously a custom layout dropped to a single stacked column).
• internal/tui gained reusable widgets — Bar, Gauge, Sparkline,
  Columns, ColumnCount, HumanBytes, HumanDuration moved out of the
  dashboard so the toolkit stays UI-agnostic and reusable (domain colouring stays
  in the dashboard).

Fixed

• kay version on local builds — when not built via GoReleaser it now falls
  back to the VCS revision/date Go embeds (kay dev (rev abc1234, <date>, dirty))
  instead of a bare dev.

Added

• ? help overlay — press ? in the dashboard or kay fleet for a
  full, context-grouped key-binding reference; any key closes it. Footers now
  advertise ? help.

• Better command help — every subcommand accepts -h/--help and prints its
  flags cleanly (exit 0), and kay with no arguments now leads with examples.

• More Overview panels & metrics — the batched metrics script (still one SSH
  round-trip) now also collects per-core CPU, swap and cached memory,
  inode usage per filesystem, TCP connection counts (/proc/net/sockstat),
  failed systemd units, and the kernel / OS release. The Overview gains
  dedicated Memory (RAM + swap + cached), Disk (space + inodes),
  Connections (active / time-wait), and Services (failed units) panels; the
  System panel shows a per-core level strip (core ▇▂▅▂) and the header shows the
  OS. All eight panels are reorderable/hideable via the o editor and now lay out
  as an ordered grid (row-major, honouring your panel order) that fills the width
  with a divider between columns.

• Customisable Overview — press o in the dashboard's Overview tab to reorder
  its panels (System, Top processes, Network, Docker) and hide the ones you don't
  want: j/k select, J/K move, space toggle, w save, Esc cancel. The
  layout persists in config.json under a new ui section and applies to every
  host. The config file gains a version field; older files (no version) load
  unchanged and are upgraded in place on the next save — no migration step, no
  data loss.

• Fleet drill-in — press Enter on a host in kay fleet to open its full
  dashboard, and Esc/q to return to the overview; Ctrl-C (or SIGTERM) exits the
  whole app. A single screen and input reader are shared for the session, so the
  handoff is seamless (no flicker) and there are never two goroutines competing
  for stdin. Internally fleet.RunView/dashboard.RunView run a view against a
  caller-owned screen + event channel; cmd/kay coordinates the two. kay fleet
  gains --read-only for the drilled-in dashboard.

• Per-host fleet state — the fleet overview now collects each host
  independently and streams results in as they arrive, so one slow or unreachable
  host no longer freezes the whole view or blocks input. The overview is
  interactive immediately; Enter on a host that is still connecting or offline
  shows a brief message instead of drilling in, and only ready hosts open.

• Top containers (docker stats) — press t in the dashboard's Docker tab
  to open a live, sortable "top containers" overlay: CPU%, memory% (coloured),
  memory usage, and net I/O per container, sorted by CPU (c) or memory (m),
  with r to reload. The query is slow, so it runs on-demand and asynchronously
  with a loading state (Esc cancels) — the periodic snapshot stays fast.

• Disk explorer — press Enter (or l) on a mount in the dashboard's Disk tab
  to drill into it: directories (recursive du size) and files (size via
  find) are listed largest-first, showing the name and extension. Enter/l/→
  descends into a directory, h/←/Backspace goes up (never above the mount), and
  Esc exits. Dotfiles are hidden by default; . toggles them and shown hidden
  entries are dimmed and tagged. Opening a file raises a dismissable
  "not supported" notice. Scans run on-demand over SSH, one level at a time, and
  asynchronously with a loading state so the dashboard stays responsive on
  large trees; keys are ignored mid-scan (except Esc to cancel). Paths are
  single-quoted so names with spaces or shell metacharacters are inert.

• Vim-friendly keys — the dashboard is consistent across every tab and
  overlay: h/j/k/l to move, g/G for ends, H/L to switch tabs, and
  Esc/q to back out.

Changed

• Persistent fleet connections — kay fleet now keeps one long-lived,
  self-healing SSH connection per host and reuses it for every refresh, instead
  of dialing a brand-new connection each tick. Reusing the transport skips the
  KEX + public-key-auth handshake on all but the first connect, which cuts CPU,
  network round-trips, and — most visibly on the server — the connection churn
  that spams auth.log and pressures sshd's MaxStartups. A shared dial cap
  bounds concurrent connects so a large fleet's cold start can't self-throttle,
  and reconnects use exponential backoff with jitter. Drilling into a host now
  reuses the connection the fleet already established (no second handshake),
  and the drilled-in dashboard inherits the connection's self-healing. New
  internal/sshx types Pool and Managed implement this, stdlib-only.

• Responsive startup — the dashboard's first metric collection now runs
  asynchronously behind a "connecting…" screen instead of blocking, and both the
  dashboard and kay fleet ignore input (except quit) until the first data
  arrives. Keys pressed during the initial 1–3 s connect no longer queue up and
  fire when the view appears.