Status page: what needs attention first, glyphs for what repeats

The page opened with every session in bold green, the normal state, and
the brightest numbers on it were the rejection counts, which RPKI doing
its job produces by the thousand. The two sessions that were actually
down were in the same red, thirty rows down. Now:

- A status line at the top says what needs attention, by name and with
  the reason: sessions down, peers restarting, the kernel behind or
  refusing routes, RPKI data missing or about to expire. When nothing
  does, it says so. A second line gives the normal state in grey.
- Colour means one thing each. Red: failed, needs a hand. Amber:
  degraded, worth watching. Green, set small: a system doing its job.
  Grey: inactive and expected. Normal is black; "Established" is no
  longer green, and a rejection count no longer red.
- Peers that need attention come first, then the others grouped by what
  they are to us, with a "problems only" switch. Numbers are right
  aligned with thousands separators; the established time and uptime
  are one cell; the session's properties are glyphs (v4, v6, GR, ENH,
  AP, 2B) with the meaning as a tooltip, as are the roles.
- Received routes: the best route leads, marked ★; attributes without a
  column are glyphs (OTC, AA, AGG, AS4, OID, CL); validity is ✓ ✗ –.
- Rejected routes: those alike (same prefix, reason and path) are one
  row with a count and the last time; each peer's reasons are a bar.
- Communities with a configured name (community_names, new) are badges
  with that name, the number as the tooltip: "comrack", "SwissIX",
  "interconnection 2011" rather than 210036:100:2 and so on. A name for
  a pattern shows the open part after it. The daemon does nothing with
  the names but pass them to the page.
- One lookup box at the top, which takes a peer's name too; a peer's
  name anywhere on the page leads to its routes; table headers and the
  status line stay in view while scrolling.
- The host name comes from gethostname(2), not from running `hostname`,
  which a static binary on a bare machine could not find: comrack said
  "unknown host".

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

Cargo.lock

@@ -312,6 +312,7 @@ dependencies = [
  "bgp-rpki",
  "bgp-server",
  "futures",
+ "nix",
  "prometheus",
  "serde",
  "tokio",