v0.10.0 — Live metrics, per-stack updates, table filtering & update terminals

Frontend-focused release building on v0.9.0:

• Metrics: reworked the stack metrics tab into a consolidated live overview
  (summary tiles + dense per-container table), removing the non-functional time
  dropdown. Fixes two backend data bugs surfaced in testing — CPU read 0% on
  cgroup v2 hosts (now uses OnlineCPUs), and network/block I/O were cumulative
  counters mislabelled as rates (now true per-second deltas).
• Per-stack Updates tab: each stack now surfaces its own update-event history,
  scoped via the existing history endpoint, instead of only the global page.
• Text filtering: sidebar-style instant text filter (reusable useTextFilter +
  TableSearch) wired across every table and overview — dashboard resource tabs,
  update log, settings, and stack views.
• Update terminals: extracted a reusable full-width UpdateJobLog. The Updates
  tab log now opens as a full-width row under the line item (was a tiny in-cell
  box), and stack-level updates gained a collapsible live "Update output"
  terminal under the header (previously toast-only). Update jobs remain
  decoupled from the client connection (background goroutine), so dropping the
  proxy mid-update does not abort the recreate.