fix(checks): process check is opt-in for url-fronted services

The ontology's stated intent was "http when it has a url, else a process
check", but the implementation emitted BOTH for every url-service — so ~17
fronted services carried a redundant process check that, under worst-of
aggregation, let a fragile supplementary probe (wrong unit name, unreachable
host, no guest agent) veto two healthy http checks and report the service
"down" while it was up (authentik, zimaos, house, matrix, ...).

buildKind now emits a process check only for services WITHOUT a url, or when
an explicit probe_unit opts into binary-level depth. http is the canonical
service-liveness probe (tests the real endpoint through the TLS terminator);
the redundant process checks were removed.

seeds/inventory.yaml

@@ -217,8 +217,7 @@ entities:
   - {slug: "service:proxmox-ui", type: service, name: proxmox_ui,
      attributes: {url: "https://proxmox.hubris.network", port: 8006,
                   doc_page: knowledge/wiki/hosts/hubris.md,
-                  risk_notes: "hypervisor UI — changes affect every guest on the node",
-                  probe_unit: pveproxy.service}}
+                  risk_notes: "hypervisor UI — changes affect every guest on the node"}}
   - {slug: "service:gitea", type: service, name: gitea,
      attributes: {url: "https://git.hubris.network", port: 3000,
                   doc_page: knowledge/wiki/containers/104-gitea.md,
@@ -240,8 +239,7 @@ entities:
                   risk_notes: "native Authentik OIDC (no forward-auth gate); VAAPI depends on GPU passthrough on strong"}}
   - {slug: "service:nextcloud", type: service, name: nextcloud,
       attributes: {url: "https://cloud.hubris.network",
-                   doc_page: knowledge/wiki/containers/114-nextcloud.md,
-                   probe_unit: apache2.service}}
+                   doc_page: knowledge/wiki/containers/114-nextcloud.md}}
   - {slug: "service:paperless", type: service, name: paperless,
      attributes: {url: "https://paperless.hubris.network",
                   doc_page: knowledge/wiki/containers/103-paperless.md,
@@ -252,8 +250,7 @@ entities:
                   risk_notes: "alert/approval channel for Oikos — outage silences agent escalation"}}
   - {slug: "service:photos", type: service, name: photos,
       attributes: {url: "https://photos.hubris.network",
-                   doc_page: knowledge/wiki/containers/120-mule-images.md,
-                   probe_unit: pp-app}}
+                   doc_page: knowledge/wiki/containers/120-mule-images.md}}
   - {slug: "service:arr-stack", type: service, name: arr_stack,
      attributes: {doc_page: knowledge/wiki/containers/122-arriman.md,
                   note: "jellyseerr / qbit / sab on docker compose"}}