feat(ui): status_badge, status_dot, stat_tile, empty_state, page_header, icon_button and form classes (#5094)

#5094 "Status and layout macros, and form classes".

- formatting.STATES: one state -> (tone, label) map for up, down, stale,
  firing, pending, acknowledged, no_data, ok, warn, crit, resolved and
  inactive; status_info() reads it (an unmapped state is drawn dim under its
  own name). required() lets a macro refuse a missing argument.
- _macros.html: status_badge and status_dot (a dot always carries its label,
  sr-only unless shown), stat_tile, empty_state, page_header (actions via a
  call block) and icon_button, which raises without a label.
- steward.css: tone classes (badge-/dot-/stat- ok, warn, crit, info, dim),
  .sr-only, .page-header, .stat-tile, .empty-state, .btn-icon and the form
  classes .field, .field-label, .field-hint and .input. Info text is a 40%
  mix (--blue): the house --fs-info-fg falls to 4.18:1 on its tint over a
  hovered row, 40% holds 5.09:1.
- First users: the Alerts list, history and maintenance pages (headers,
  state badges, empty states) and the alert forms' hints; the inline inp/lbl
  style sets on the monitor and host forms become .input / .field-label.
- tests/core/test_macros.py renders each macro through the app environment.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

steward/core/formatting.py

@@ -95,3 +95,37 @@ def status_class(value: Any, kind: str, thresholds: dict) -> str:
     if th.get("dir", "high") == "low":
         return "crit" if value < crit else "warn" if value < warn else "ok"
     return "crit" if value >= crit else "warn" if value >= warn else "ok"
+
+
+# Every state a page shows, and the tone it is drawn in: ok (green), warn
+# (amber), crit (red), info (blue) or dim. The status_badge and status_dot
+# macros read this, so one state looks the same on every page.
+STATES: dict[str, tuple[str, str]] = {
+    "up": ("ok", "Up"),
+    "ok": ("ok", "OK"),
+    "resolved": ("ok", "Resolved"),
+    "down": ("crit", "Down"),
+    "firing": ("crit", "Firing"),
+    "crit": ("crit", "Critical"),
+    "warn": ("warn", "Warning"),
+    "pending": ("warn", "Pending"),
+    "stale": ("warn", "Stale"),
+    "no_data": ("warn", "No data"),
+    "acknowledged": ("info", "Acknowledged"),
+    "inactive": ("dim", "Inactive"),
+    "unknown": ("dim", "Unknown"),
+}
+
+
+def status_info(state: Any) -> tuple[str, str]:
+    """(tone, label) for a state name or enum. A state the map doesn't know
+    is drawn dim under its own name rather than breaking the page."""
+    key = str(getattr(state, "value", state) or "unknown").lower()
+    return STATES.get(key, ("dim", key.replace("_", " ").capitalize()))
+
+
+def required(value: Any, what: str) -> Any:
+    """For a macro argument that must be given: raise if it is empty."""
+    if value is None or not str(value).strip():
+        raise ValueError(f"{what} is required")
+    return value