v0.1.2

Internal cleanup: no behavior change and no new features. Reduces duplication,
splits an oversized file, tightens package seams, and makes the interactive code
testable (total coverage 66.9% → 73.7%).

Changed

• Shared UI helpers — moved the duplicated setColor, clampAll,
  firstLine, and colour-threshold logic out of dashboard and fleet into the
  tui toolkit (SetColorMode, ClampAll, FirstLine, ThreshColor). No
  behavior change; both views now share one source of truth for colour and
  layout.
• Split dashboard.go — the 1200-line file is now four focused files in the
  same package: dashboard.go (lifecycle + data), input.go (keys/actions),
  render.go (view builders), and format.go (pure formatting helpers). Pure
  code move, no behavior change.
• Unified the SSH seam — dashboard.Client is now an alias of
  metrics.Runner, so the dashboard and the metrics collector share one
  interface instead of two identical copies.
• Split tui.List into List + Pager — the selectable list and the
  scrollable overlay were one dual-mode type gated by a selectable flag;
  they are now two focused widgets (List.Render(w, h) drops the flag), which
  removes the never-used pager branch from the list path.
• Raised sshx coverage from ~48% to ~72% with white-box tests for the
  non-interactive helpers (termType, classifyDialError, contains,
  appendKnownHost, confirmHost, and the hostKeyCallback pinning/rejection
  paths). The remaining gap is interactive (Shell, terminal read).
• Testability seams — extracted terminal-independent cores so the
  interactive paths can be tested without a real TTY, with no behavior change:
  the host-key TOFU prompt (confirmHost), the key passphrase decrypt path
  (parseSigner), and the dashboard/fleet event loops (loop, driven by an
  injected screen interface and input/signal/tick channels). Total coverage
  rose from ~67% to ~74% (dashboard 80%, fleet 62%, sshx 72%, keys 77%).