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/templates/alerts/rules_form.html

@@ -47,7 +47,7 @@
           <select name="resource_name" required disabled>
             <option value="">No data yet — run monitors first</option>
           </select>
-          <p style="font-size:0.78rem;color:var(--text-muted);margin-top:0.25rem;">
+          <p class="field-hint">
             Resource names populate from live metric data. Start the scheduler and try again.
           </p>
           {% endif %}
@@ -94,7 +94,7 @@
         <label>Consecutive OK checks before it clears</label>
         <input type="number" name="consecutive_ok_required" min="1"
                value="{{ rule.consecutive_ok_required if rule else 1 }}">
-        <p style="font-size:0.75rem;color:var(--text-muted);margin-top:0.2rem;">
+        <p class="field-hint">
           A firing or acknowledged alert resolves only after this many checks in a row are back
           within the threshold. An acknowledgement holds until then.</p>
       </div>
@@ -105,7 +105,7 @@
                  {% if not rule or rule.notify_no_data %}checked{% endif %}>
           Notify when this metric stops reporting
         </label>
-        <p style="font-size:0.75rem;color:var(--text-muted);margin-top:0.2rem;">
+        <p class="field-hint">
           Silence is always shown as NO DATA on the Alerts page: no sample for three of the
           metric's usual gaps (at least 5 minutes). This also sends a notification when it starts
           and when data resumes. A firing alert that goes silent stays firing.</p>
@@ -147,7 +147,7 @@
           } %}
           {% for src, pairs in descs.items() %}
           <div>
-            <div style="font-size:0.78rem;font-weight:600;color:var(--text-dim);text-transform:uppercase;letter-spacing:0.05em;margin-bottom:0.2rem;">{{ src }}</div>
+            <div style="font-size:0.78rem;font-weight:500;color:var(--text-dim);text-transform:uppercase;letter-spacing:0.05em;margin-bottom:0.2rem;">{{ src }}</div>
             {% for metric, desc in pairs %}
             <div style="display:grid;grid-template-columns:160px 1fr;gap:0.5rem;font-size:0.78rem;padding:0.15rem 0;">
               <code>{{ metric }}</code>
@@ -163,7 +163,7 @@
       {% if session.get("user_role") == "admin" %}
       {% set act = rule.ansible_action if rule and rule.ansible_action else None %}
       <div style="margin:1.25rem 0;padding:1rem;border:1px solid var(--border-mid);border-radius:6px;background:var(--bg-elevated);">
-        <label style="display:flex;align-items:center;gap:0.5rem;font-weight:600;">
+        <label style="display:flex;align-items:center;gap:0.5rem;font-weight:500;">
           <input type="checkbox" name="ansible_enabled" {% if act %}checked{% endif %}>
           On firing → run an Ansible playbook
         </label>