feat(hosts): re-provision action on reporting hosts; Ansible off the edit page

- Host agent panel (reporting state) gains a "Re-provision" collapsible (admin +
  linked target + managed key): bootstrap user/password → provision.yml, which
  reinstalls the steward account + managed key + agent. This is the missing path
  after regenerating the managed key — Update alone can't fix a broken key.
- Remove the Ansible sections (run-playbook + target link) from the host EDIT
  page — they were the stale free-text version and the wrong place. They live on
  the host detail hub (dropdown + discovered variables). Edit page now links to
  the host page; edit_host route simplified (no ansible fetch).

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

steward/hosts/routes.py

@@ -304,38 +304,16 @@ async def create_host():
 @hosts_bp.get("/<host_id>/edit")
 @require_role(UserRole.operator)
 async def edit_host(host_id: str):
-    from steward.models.ansible_inventory import AnsibleTarget
-    from sqlalchemy.orm import selectinload
-
+    # Pure host config (name/address/monitors). Agent, Ansible target linking,
+    # and playbook runs live on the host detail page (the hub), not here.
     async with current_app.db_sessionmaker() as db:
         result = await db.execute(select(Host).where(Host.id == host_id))
         host = result.scalar_one_or_none()
         if host is None:
             return "Not found", 404
 
-        linked_result = await db.execute(
-            select(AnsibleTarget)
-            .where(AnsibleTarget.host_id == host_id)
-            .options(selectinload(AnsibleTarget.groups))
-        )
-        linked_target = linked_result.scalar_one_or_none()
-
-        # Only show targets not yet linked to any host (plus the currently linked one)
-        linkable_result = await db.execute(
-            select(AnsibleTarget)
-            .where(AnsibleTarget.host_id.is_(None))
-            .order_by(AnsibleTarget.name)
-        )
-        linkable_targets = linkable_result.scalars().all()
-
     return await render_template(
-        "hosts/form.html",
-        host=host,
-        probe_types=list(ProbeType),
-        ansible_sources=_ansible_source_names(),
-        linked_target=linked_target,
-        linkable_targets=linkable_targets,
-    )
+        "hosts/form.html", host=host, probe_types=list(ProbeType))
 
 
 @hosts_bp.post("/<host_id>")