feat(plugins): fold first-party plugins in-tree; bundled + external roots

First-party plugins (host_agent, http, snmp, traefik, unifi, docker) are now
tracked under plugins/ and baked into the image, so they version atomically
with core — ending the cross-repo import drift the roundtable->steward rename
exposed. History for these files is preserved in the archived Roundtable-plugins
repo.

Plugin discovery becomes multi-root: PLUGIN_DIR (single) -> PLUGIN_DIRS
(bundled first, then external) + PLUGIN_INSTALL_DIR. Bundled ships in the image;
third-party plugins still mount at runtime into the external root
(STEWARD_PLUGIN_DIR, default /data/plugins) and downloads/installs land there.
Bundled shadows external on a name collision.

- config.py: load_bootstrap returns plugin_dirs + plugin_install_dir
- app.py: iterate PLUGIN_DIRS at the migration + load sites
- migration_runner.py: discover_all_in() unions every plugin root
- plugin_manager.py: resolve_plugin_path() (pure, first-root-wins); load /
  install / hot-reload span all roots; installs target the external root
- settings/routes.py: _discover_plugins scans all roots, dedup bundled-first
- Dockerfile: COPY plugins/ ; docker-compose: drop host bind, document external
- tests/test_plugin_dirs.py: resolution, multi-root discovery, bootstrap split

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

plugins/docker/templates/docker/rows.html

@@ -0,0 +1,86 @@
+{# docker/rows.html — HTMX fragment for the Docker main page #}
+
+{# ── Summary strip ─────────────────────────────────────────────────────────── #}
+<div style="display:grid;grid-template-columns:repeat(auto-fill,minmax(140px,1fr));gap:0.75rem;margin-bottom:1.5rem;">
+  <div class="card" style="margin-bottom:0;">
+    <div class="section-title" style="margin-bottom:0.35rem;">Running</div>
+    <span class="stat-val" style="color:var(--green);">{{ running }}</span>
+  </div>
+  <div class="card" style="margin-bottom:0;">
+    <div class="section-title" style="margin-bottom:0.35rem;">Stopped</div>
+    <span class="stat-val" style="{% if stopped %}color:var(--text-muted){% endif %};">{{ stopped }}</span>
+  </div>
+  <div class="card" style="margin-bottom:0;">
+    <div class="section-title" style="margin-bottom:0.35rem;">Total</div>
+    <span class="stat-val">{{ container_data | length }}</span>
+  </div>
+</div>
+
+{# ── Container table ─────────────────────────────────────────────────────── #}
+{% if container_data %}
+<div class="card-flush">
+  <table class="table">
+    <thead>
+      <tr>
+        <th>Container</th>
+        <th>Image</th>
+        <th>Ports</th>
+        <th>CPU %</th>
+        <th style="min-width:100px;">CPU history</th>
+        <th>Mem %</th>
+        <th style="min-width:100px;">Mem history</th>
+      </tr>
+    </thead>
+    <tbody>
+      {% for item in container_data %}
+      {% set c = item.container %}
+      <tr>
+        <td>
+          <div style="display:flex;align-items:center;gap:0.5rem;">
+            <span class="dot {% if c.status == 'running' %}dot-up{% elif c.status == 'paused' %}dot-warn{% else %}dot-down{% endif %}"></span>
+            <div>
+              <div style="font-weight:500;font-size:0.9rem;">{{ c.name }}</div>
+              <div style="font-size:0.73rem;color:var(--text-muted);">{{ c.status }}</div>
+            </div>
+          </div>
+        </td>
+        <td style="font-size:0.82rem;color:var(--text-muted);max-width:200px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;">
+          {{ c.image }}
+        </td>
+        <td style="font-size:0.78rem;font-family:ui-monospace,monospace;">
+          {% for p in item.ports %}
+          <div style="color:var(--text-muted);">{{ p.host_port }}:{{ p.container_port }}/{{ p.protocol }}</div>
+          {% endfor %}
+        </td>
+        <td style="font-family:ui-monospace,monospace;font-size:0.88rem;">
+          {% if c.cpu_pct is not none %}
+          <span style="color:{% if c.cpu_pct > 80 %}var(--red){% elif c.cpu_pct > 50 %}var(--orange){% else %}var(--text){% endif %};">
+            {{ "%.1f" | format(c.cpu_pct) }}%
+          </span>
+          {% else %}
+          <span style="color:var(--text-dim);">—</span>
+          {% endif %}
+        </td>
+        <td>{{ item.sparkline_cpu | safe }}</td>
+        <td style="font-family:ui-monospace,monospace;font-size:0.88rem;">
+          {% if c.mem_pct is not none %}
+          <span style="color:{% if c.mem_pct > 90 %}var(--red){% elif c.mem_pct > 70 %}var(--orange){% else %}var(--text){% endif %};">
+            {{ "%.1f" | format(c.mem_pct) }}%
+          </span>
+          {% else %}
+          <span style="color:var(--text-dim);">—</span>
+          {% endif %}
+        </td>
+        <td>{{ item.sparkline_mem | safe }}</td>
+      </tr>
+      {% endfor %}
+    </tbody>
+  </table>
+</div>
+{% else %}
+<div class="card" style="text-align:center;padding:3rem;">
+  <div style="color:var(--text-muted);font-size:0.9rem;">
+    No containers found. Make sure the Docker socket is accessible and the plugin is configured correctly.
+  </div>
+</div>
+{% endif %}