feat(homeassistant): it shows system problems and installs updates on a weekly slot, and leaves device readings alone (#6748, #6749, #6747)

The connection's job is keeping Home Assistant running. Each poll now reads open
repairs, Supervisor health, disk, recovery mode and add-ons that should be running
over its websocket, for the page, the overview and the problems_open, disk_free_pct
and update_failed metrics. That needs a websocket client, so websockets joins the
dependencies.

A weekly slot, set on the page or through MCP and off until then, installs add-ons,
then Core, then the OS, each after its own confirmed backup, ending at the first
failure. The slot arithmetic moves from the host agent's cadence to steward.core.weekly
so both share it.

The device scrape goes: the page's Metrics section and a target's token_from from
4c9ed02 are removed, and a migration deletes targets using it, as they'd otherwise ask
with no token. A refused token still stops a scrape.

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

plugins/prometheus/migrations/versions/prometheus_005_own_tokens.py

@@ -0,0 +1,30 @@
+"""Every target holds its own token: one that took it from a sign-in goes
+
+Revision ID: prometheus_005_own_tokens
+Revises: prometheus_004_token_from
+Create Date: 2026-11-01
+"""
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "prometheus_005_own_tokens"
+down_revision: Union[str, None] = "prometheus_004_token_from"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # Left in place, such a target would ask with no token, and some services ban
+    # an address for that. Its newest values go with it; history ages out.
+    op.execute("""
+        DELETE FROM plugin_metric_latest l USING prometheus_targets t
+        WHERE t.token_from IS NOT NULL AND l.source_module = 'prometheus'
+          AND (l.resource_name = t.name OR left(l.resource_name, length(t.name) + 1) = t.name || ':')""")
+    op.execute("DELETE FROM prometheus_targets WHERE token_from IS NOT NULL")
+    op.drop_column("prometheus_targets", "token_from")
+
+
+def downgrade() -> None:
+    op.add_column("prometheus_targets", sa.Column("token_from", sa.String(50), nullable=True))