docs: config changes are operator merges on the forge

Rewrites the config-change flow around the forge merge and the
DeployRequest{rev} deploy, drops the MergeConfigPr approval, its deploy
DAG, the hive's `/webhook/` route and the `core` merge allowlist from
the docs, and states that operators join the `operators` team by hand.

Refs #4850

docs/agent-lifecycle/persistence.md

@@ -56,8 +56,8 @@ power-intent registry:
   per-agent store — see [`/harness/` contents
   below](#state-dirs-per-agent) for where reminders (and todos)
   live.
-- `approvals` — the queue. `agent / kind (merge_config_pr | spawn |
-  update_meta_inputs | schedule_prompt) /
+- `approvals` — the queue. `agent / kind (update_meta_inputs |
+  schedule_prompt) /
   commit_ref / requested_at / status / resolved_at / note`.
 - `scheduled_prompts` — recurring + one-shot prompt queue.
   `owner / body / interval_seconds (NULL = one-shot) /