feat(timeline): one record of what happened to the infrastructure, newest first (#6348)

A stored log, timeline_entries, with one row per thing that happened. Each
source writes its row in the same transaction as its own record, so the
history outlives the 30/90/365-day retention of the tables it points to:

- alert events (core/alerts._add_event): fired, resolved, acknowledged,
  went silent, readings back;
- finished Ansible runs (executor, and the startup sweep of interrupted
  runs): changed something, changed nothing, failed, dry run;
- audit rows (core/audit.log_audit): Steward's settings, users and access,
  sign-ins, backups. Actions another writer records are left to it.

Entries carry a kind (fixed) and an area (Service, Host OS, Hardware,
Storage, Network, Security, Monitoring). Settings → Timeline edits the
areas and each type's area and visibility; both are applied when the
timeline is read, so a change re-sorts past entries and a hidden type
comes back when shown. Kept forever unless a retention is set.

The first start fills the timeline from the last 90 days of records once,
skipping any already covered. A host rename carries its entries.

UI: Timeline in the sidebar (filter by host, area, kind; scrolls on), a
History card on each host page. MCP: get_timeline.

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

steward/templates/timeline/_entry.html

@@ -0,0 +1,21 @@
+{# One timeline entry's parts, shared by the Timeline page and a host's card.
+   `item` is a timeline.service.view() row. #}
+
+{# What happened: its kind, the sentence, a note, and the full record while it is kept. #}
+{% macro entry_what(item) -%}
+{%- set e = item.entry -%}
+<div>
+  {%- if item.kind_label %}<span class="tone-dim">{{ item.kind_label }} · </span>{% endif -%}
+  {{ e.summary }}
+</div>
+{%- if item.note %}<div class="field-hint">{{ item.note }}</div>{% endif %}
+{%- if item.url %}<div class="field-hint"><a href="{{ item.url }}">Details</a></div>
+{%- elif item.gone %}<div class="field-hint">Details no longer kept</div>{% endif %}
+{%- endmacro %}
+
+{# Where: the hosts it happened on, each linked to its timeline, and what it happened to. #}
+{% macro entry_where(e) -%}
+{%- for h in e.hosts %}<a href="/timeline/?host={{ h|urlencode }}">{{ h }}</a>{{ ", " if not loop.last }}{% endfor -%}
+{%- if e.subject and e.subject not in e.hosts %}{% if e.hosts %}<br>{% endif %}<span class="field-hint">{{ e.subject }}</span>{% endif -%}
+{%- if not e.hosts and not e.subject %}<span class="tone-dim">—</span>{% endif -%}
+{%- endmacro %}

steward/templates/timeline/_host_card.html

@@ -0,0 +1,25 @@
+{# A host's newest timeline entries, loaded into its page: what happened to it
+   lately, with the whole of it a click away. #}
+{% from "_macros.html" import empty_state %}
+{% from "timeline/_entry.html" import entry_what %}
+<section class="card" aria-labelledby="host-history">
+  <div style="display:flex;align-items:baseline;justify-content:space-between;gap:1rem;">
+    <h3 id="host-history" class="section-title">History</h3>
+    <a class="field-hint" href="/timeline/?host={{ host.name|urlencode }}">All of {{ host.name }}'s history</a>
+  </div>
+  {% if items %}
+  <table class="table">
+    <tbody>
+      {% for item in items %}
+      <tr>
+        <td class="nowrap" style="width:1%;">{{ item.entry.at|when }}</td>
+        <td>{{ entry_what(item) }}</td>
+        <td class="nowrap" style="width:1%;">{{ item.entry.actor }}</td>
+      </tr>
+      {% endfor %}
+    </tbody>
+  </table>
+  {% else %}
+  {{ empty_state("Nothing has happened to " ~ host.name ~ " that the timeline records yet.") }}
+  {% endif %}
+</section>

steward/templates/timeline/_rows.html

@@ -0,0 +1,21 @@
+{# timeline/_rows.html — one page of the timeline's rows, then the sentinel
+   that loads the next page as the reader nears it (core.paging). A divider
+   row opens each recency group: Today, Yesterday, Last 7 days, Older. #}
+{% from "_macros.html" import scroll_more, scroll_end %}
+{% from "timeline/_entry.html" import entry_what, entry_where %}
+      {% for item in items %}
+      {% set e = item.entry %}
+      {% if item.opens_group %}<tr class="table-divider"><th colspan="5" scope="rowgroup">{{ item.group }}</th></tr>{% endif %}
+      <tr>
+        <td class="nowrap">{{ e.at|when }}</td>
+        <td>{{ entry_what(item) }}</td>
+        <td>{{ entry_where(e) }}</td>
+        <td class="nowrap">{{ e.actor }}</td>
+        <td class="nowrap"><span class="chip">{{ item.area_label }}</span></td>
+      </tr>
+      {% endfor %}
+{% if after %}
+{{ scroll_more("/timeline/?before=" ~ (after|urlencode) ~ "&" ~ (keep|urlencode) ~ "&group=" ~ (last_group|urlencode), cols=5) }}
+{% else %}
+{{ scroll_end(cols=5) }}
+{% endif %}

steward/templates/timeline/list.html

@@ -0,0 +1,54 @@
+{# timeline/list.html — everything that happened to the infrastructure, newest
+   first, one list: alerts, playbook runs, changes to Steward's settings.
+   Filters are by host, area (what was affected) and kind (how it came about);
+   Settings → Timeline decides each type's area and whether it is shown, and
+   "Include hidden" shows the types it hides. #}
+{% extends "base.html" %}
+{% from "_macros.html" import page_header, empty_state %}
+{% block title %}Timeline — Steward{% endblock %}
+{% block content %}
+{% call page_header("Timeline", "What happened, newest first: alerts, playbook runs and changes, on every host.") %}
+  {% if session.user_role == 'admin' %}<a class="btn btn-ghost btn-sm" href="/settings/timeline/">Areas and types</a>{% endif %}
+{% endcall %}
+
+<form class="filter-bar" method="get" action="/timeline/" role="search">
+  <select name="host" aria-label="Host" onchange="this.form.submit()">
+    <option value="">All hosts</option>
+    {% for h in hosts %}<option value="{{ h }}"{% if filters.host == h %} selected{% endif %}>{{ h }}</option>{% endfor %}
+  </select>
+  <select name="area" aria-label="Area" onchange="this.form.submit()">
+    <option value="">All areas</option>
+    {% for key, label in areas %}<option value="{{ key }}"{% if filters.area == key %} selected{% endif %}>{{ label }}</option>{% endfor %}
+  </select>
+  <select name="kind" aria-label="Kind" onchange="this.form.submit()">
+    <option value="">All kinds</option>
+    {% for key, label in kinds.items() %}<option value="{{ key }}"{% if filters.kind == key %} selected{% endif %}>{{ label }}</option>{% endfor %}
+  </select>
+  <label class="field-hint" style="display:flex;align-items:center;gap:0.35rem;">
+    <input type="checkbox" name="hidden" value="1"{% if filters.hidden %} checked{% endif %} onchange="this.form.submit()">
+    Include hidden types
+  </label>
+  <noscript><button type="submit" class="btn btn-ghost btn-sm">Filter</button></noscript>
+</form>
+
+{% if items %}
+<div class="card-flush">
+  <table class="table">
+    <thead>
+      <tr>
+        <th>When ({{ tz_label() }})</th>
+        <th>What happened</th>
+        <th>Where</th>
+        <th>Who</th>
+        <th>Area</th>
+      </tr>
+    </thead>
+    <tbody>
+      {% include "timeline/_rows.html" %}
+    </tbody>
+  </table>
+</div>
+{% else %}
+<div class="card">{{ empty_state("Nothing on the timeline matches these filters." if keep else "Nothing has been recorded on the timeline yet.") }}</div>
+{% endif %}
+{% endblock %}