feat(status): unified Status page + widget across ping/DNS/HTTP monitors

Adds a Kuma-style "is everything up?" surface that aggregates heterogeneous
monitor types via a status-source registry (steward/core/status.py): each
type registers an async source(db) -> [StatusEntry]. Core registers ping/DNS;
the http plugin registers its own from setup() so core never imports plugin
tables. Per entry: current up/down, last-30 heartbeat bar, uptime %
(24h/7d/30d), latest latency + response sparkline, and TLS expiry countdown
(HTTP). New /status page (live htmx refresh) + a status_overview dashboard
widget + nav link. Pure-function unit tests for registry + sparkline.

First deliverable of milestone #68 (task #866).

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

steward/status/__init__.py

@@ -0,0 +1 @@
+# steward/status/ — unified monitor-status surface (page + dashboard widget)

steward/status/routes.py

@@ -0,0 +1,51 @@
+from __future__ import annotations
+from quart import Blueprint, current_app, render_template, request
+
+from steward.auth.middleware import require_role
+from steward.core.status import collect_status, sparkline_svg
+from steward.models.users import UserRole
+
+status_bp = Blueprint("status", __name__, url_prefix="/status")
+
+
+def _summarize(entries) -> tuple[int, int, int]:
+    up = sum(1 for e in entries if e.status == "up")
+    down = sum(1 for e in entries if e.status == "down")
+    pending = sum(1 for e in entries if e.status == "pending")
+    return up, down, pending
+
+
+@status_bp.get("/")
+@require_role(UserRole.viewer)
+async def index():
+    poll_interval = current_app.config.get("MONITORS_POLL_INTERVAL", 60)
+    return await render_template("status/index.html", poll_interval=poll_interval)
+
+
+@status_bp.get("/rows")
+@require_role(UserRole.viewer)
+async def rows():
+    """HTMX fragment — the full status list + summary, refreshed on poll."""
+    async with current_app.db_sessionmaker() as db:
+        entries = await collect_status(db)
+    for e in entries:
+        if e.spark:
+            e.spark_svg = sparkline_svg(e.spark)
+    up, down, pending = _summarize(entries)
+    return await render_template(
+        "status/rows.html", entries=entries, up=up, down=down, pending=pending
+    )
+
+
+@status_bp.get("/widget")
+@require_role(UserRole.viewer)
+async def widget():
+    """HTMX dashboard widget — compact up/down/pending summary + problem list."""
+    async with current_app.db_sessionmaker() as db:
+        entries = await collect_status(db)
+    up, down, pending = _summarize(entries)
+    return await render_template(
+        "status/widget.html",
+        entries=entries, up=up, down=down, pending=pending,
+        widget_id=request.args.get("wid", "0"),
+    )