feat(observability): restore monitoring coverage, make gaps visible, stream executions

Monitoring coverage was 3 of 89 active entities. Three bugs, each hidden by
discarded errors in checkdefaults:

- writeCheck generated a fresh uuid, inserted the check entity ON CONFLICT
  (slug) DO NOTHING, then wrote a check_defs row referencing it. On any
  re-seed the slug already existed, the entity insert no-oped, and the FK
  violated — aborting the ingest transaction and surfacing as an unrelated
  failure several entities later. Re-seeding has been broken since; prod's
  coverage was frozen at its first successful seed. This is what
  TestSeedIngestIdempotentAndNoDuplicateEdges had been reporting.
- shortSlug truncated to the last 8 chars, so all 21 ingress routes collapsed
  to ".network" and overwrote each other; service:jellyfin collided with
  lxc:jellyfin.
- The ssh-script checker never read the `args` config checkdefaults wrote, so
  process_check.sh always ran without its unit name and returned "unknown".

Coverage is now 75/89. Monitoring is declared per entity type in
seeds/ontology.yaml and resolved through the is-a hierarchy, so a type can say
it warrants nothing (site, lan, mesh, cluster) and never be reported as a gap.
coverageSweep raises an `unmonitored` signal only where a type declares
monitoring it lacks — 8 real gaps, no false positives.

Also:
- entity_types.attribute_schema was never ingested: the seed loader read
  "attribute_schema" but the YAML says "attributes", so all 60 types stored
  JSON null.
- ListExecutions ignored its declared target/action/correlation_id filters and
  paginated on a non-unique target slug, dropping and repeating rows.
- started_at was captured but only written at terminal state, so a running
  execution reported NULL for its whole life. The three MCP auto-run copies
  wrote no timing at all; they are now one autoRun helper.
- SSH output was buffered to completion and discarded entirely on timeout.
  Both sshExec copies now stream through a shared execlog sink into
  execution_logs, and keep partial output when a command is cancelled.
- executions.correlation_id was a random per-execution uuid that correlated
  nothing; it is now the chat session id, which is what lets the chat tail
  live output.
- reversible_low had no auto-run branch despite policy declaring it
  unattended. Since computeCommandRisk never returns it, the class only arises
  when an agent declares it over a read_only command — so gating it penalised
  candor without adding safety.
- backup-target gains a backup-freshness checker (portable find -mmin, since
  the first target is on macOS), resolving its host by walking backs-up-to
  backwards. The pre-deploy pg_dump is now a tracked backup target.

UI: an Executions section on entity detail with live output tailing, and
streamed output under a running `run` call in the chat timeline.

Migrations 022-024. Ops.svelte and context.ts exclude execution.output from
their refetch triggers, which would otherwise fire once a second per command.

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

seeds/policy.yaml

@@ -44,6 +44,23 @@ risk_classes:
     autonomy_allowed: false
 
 approval_rules:
+  # Signal kinds are looked up as `action` by internal/policy/classify.go, and
+  # an unmatched kind silently falls back to reversible_low/operator. Declare
+  # `unmonitored` so its routing is intentional: it reports a coverage gap and
+  # there is nothing to remediate automatically — closing it means an operator
+  # adding a check_def, which is its own deliberate change.
+  - {entity_type: entity, action: unmonitored, risk_class: read_only, autonomy_level: auto}
+
+  # Backup freshness signals. Reporting-only for the same reason: the fix for a
+  # stale or missing backup is a deliberate human change (re-run the job, fix
+  # the mount, correct the path), never something to auto-remediate. Declared
+  # so the routing is intentional rather than the reversible_low/operator
+  # fallback an unmatched kind would otherwise get.
+  - {entity_type: backup-target, action: backup-stale, risk_class: read_only, autonomy_level: auto}
+  - {entity_type: backup-target, action: backup-missing, risk_class: read_only, autonomy_level: auto}
+  - {entity_type: backup-target, action: backup-misconfigured, risk_class: read_only, autonomy_level: auto}
+  - {entity_type: backup-target, action: backup-unreachable, risk_class: read_only, autonomy_level: auto}
+
   # ── Generic rules on (possibly abstract) types ──
   - {entity_type: service, action: restart, risk_class: reversible_low, autonomy_level: auto}
   - {entity_type: service, action: cache-clear, risk_class: reversible_low, autonomy_level: auto}