docs(pm-agent): CLAUDE.md §0 is already satisfied in a worker — tell it not to make a worktree

PR #56 added §0 (work in your own worktree, never the shared checkout) while this branch
was open. A worker agent reads CLAUDE.md first, and §0's instruction is to create a git
worktree outside the shared checkout — which does not exist in a worker's container. It
holds a fresh clone of its own, made for one assignment and thrown away with the pod,
which is what §0 is actually asking for.

A worker that obeyed §0 literally would 'git worktree add', edit somewhere the wrapper
that started it does not look, and have its work committed by nobody while the issue got
a 'changed nothing' report. worker-rules.md now says §0 is satisfied and not to do that.

Also records in the handoff entry: the merge and its one conflict, and that this push
dismisses the operator's approving review — measured, dismiss_stale_approvals=true — so
the approval-policy stage needs them to re-approve. That is theirs to do, not an agent's.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

infra/agent/worker-rules.md

@@ -15,6 +15,13 @@ facts about the container you are running inside.
   pinned toolchain is on `PATH` — you are *inside* the toolbox, so run `./ci/gate.sh`
   directly. Do **not** try to run `infra/devcontainer/dev.sh`; there is no container engine
   here and no need for one.
+- **`CLAUDE.md` §0 is already satisfied. Do not make a worktree.** §0 tells agents to work in
+  a git worktree outside the shared checkout, because that checkout is the operator's working
+  copy and several runs fight over its HEAD. There is no shared checkout here: this container
+  holds a fresh clone of its own, made for this assignment and thrown away with the pod, which
+  is what §0 is asking for. `git worktree add` would put your edits somewhere the wrapper that
+  started you does not look — so your work would be committed by nobody and the issue would
+  get a "changed nothing" report. Work in the tree you are standing in.
 - You hold **no cluster credentials** — no kubeconfig, and no ServiceAccount token is
   mounted. `kubectl` is on `PATH` and will fail. That is deliberate: you cannot measure the
   live platform, so do not claim to have. Anything that needs a cluster is a line in "What