Fix the finish review's 8 material findings on the teletext redesign

Applies the fix round from the finish-reviewer's disposition on commit
4b19cbd, in one batch:

- System's disk table is unreadable below 560px: horizontal-scrolling a
  6-column table hid the usage bar and the temperature, the two
  readings that matter most (discipline 3 — one shared ruler — was
  unauditable as a result). Added a disk_row() macro and a phone-only
  .tt-disk-rows reflow (name + full 20-cell bar + temp on one line,
  device/free/total beneath), CSS-toggled against the existing table
  at the same breakpoint.
- Contrast failure on the highest-severity state: white text on the
  red .tt-field.crit/.tt-toast.error/.tt-btn.armed reversals measured
  4.0:1, under the 4.5:1 floor. Switched to black text (5.25:1),
  matching the black-on-yellow .warn pattern already in use — and
  fixed a second instance of the same bug: .tt-field.crit had no
  .tt-field-meta override, unlike .warn.
- Two type families where the direction contract names one blocky
  monospace: unified on a single self-hosted face (Space Mono, one
  weight, no bold) for both body and the double-height row.
- FIRST VIEWPORT proportion: an unpromised 6-item Just Added grid was
  competing with NOW SHOWING for the fold instead of the contract's
  "lower two-thirds in double-height cyan." Cut to a fixed 3-item,
  fixed-3-column row, which also fixes the orphaned-tile grid defect
  as a side effect (a fixed count can't leave a lone tile beside empty
  tracks).
- Three flat mid-grey fills contradicted discipline 1 (no in-between
  tone): .tt-tile-art, .tt-btn:disabled, and .tt-err pre all painted a
  solid --ink-dimmer background. Centralized the dither .tt-tile-art
  already used correctly into a shared --dither-mid generator and
  applied it to all three.
- Google Fonts dependency on a LAN-only home server: a dropped webfont
  request was a silent identity change, not a graceful fallback.
  Self-hosted Space Mono under static/fonts/ via @font-face; dropped
  the <link> tags from _shell.html and login.html.
- Deliberately deferred: "pages differ in stock" (discipline 5) still
  fires on only one band service-wide. Every other finding was a
  bounded fix to existing code; this one asks for a new mechanism (an
  aggregate status band on P100) rather than a correction, so it's
  flagged for a follow-up rather than rushed into this batch.

Recaptured desktop.png, mobile.png, desktop-system.png and
mobile-system.png (the four files the reviewer's findings cited)
through the same true-390px iframe method as the prior round, and
returned them for the fix round's verdict pass.

Known follow-up: DESIGN.md's typography section (written by the
documenter before this batch) still names the old two-family pairing
and needs a re-run now that the font system changed under it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NBw1QodG8ZMYHrGeQfqyDS

templates/_shell.html

@@ -7,9 +7,10 @@
   <title>{% block title %}P{{ here[1] }} Media Centre{% endblock %}</title>
   <meta name="theme-color" content="#000000">
   <link rel="icon" href="{{ url_for('static', filename='favicon.svg') }}">
-  <link rel="preconnect" href="https://fonts.googleapis.com">
-  <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
-  <link href="https://fonts.googleapis.com/css2?family=Chivo+Mono:wght@400;600&family=DotGothic16&display=swap" rel="stylesheet">
+  {#- Space Mono is self-hosted (see base.css's @font-face) — this app
+      runs on a LAN-only home server where a Google Fonts request can
+      simply fail, and a dropped webfont request is a silent identity
+      change, not a graceful fallback. -#}
   <link rel="stylesheet" href="{{ url_for('static', filename='css/base.css') }}">
   <link rel="stylesheet" href="{{ url_for('static', filename='css/teletext.css') }}">
   {% block css %}{% endblock %}