chore: single-source the never-rewrite-history policy as a generated block (#384)

Replace the hand-maintained history-rewrite guidance with the generated
repos_sync:history block (byte-identical canonical text from
PyAutoMind/policy/never_rewrite_history.md), so the safety policy is
single-sourced and drift-checked. The text stays inline; only the manual copy
is retired. Part of the ecosystem standardization (spec 4).


Claude-Session: https://claude.ai/code/session_01KUGujq6jAgU3CExnLkkELe

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: Jammy2211

AGENTS.md

@@ -118,14 +118,28 @@ from `AbstractNDArray`; `.array` returns the raw `numpy.ndarray` / `jax.Array`.
 - [`docs/agents/jax_and_decorators.md`](docs/agents/jax_and_decorators.md) —
   decorator system, `xp` backend pattern, and the `jax.jit` boundary.
 
-## Clean state
-
-Never rewrite history on a repo with a remote (no `git init` over a tracked
-tree, no force-push to `main`, no rebasing pushed shared branches). To reset a
-dirty tree the only correct sequence is:
-
-```bash
-git fetch origin
-git reset --hard origin/main
-git clean -fd
-```
+<!-- repos_sync:history:begin -->
+## Never rewrite history
+
+NEVER perform these operations on any repo with a remote:
+
+- `git init` in a directory already tracked by git
+- `rm -rf .git && git init`
+- Commit with subject "Initial commit", "Fresh start", "Start fresh", "Reset
+  for AI workflow", or any equivalent message on a branch with a remote
+- `git push --force` to `main` (or any branch tracked as `origin/HEAD`)
+- `git filter-repo` / `git filter-branch` on shared branches
+- `git rebase -i` rewriting commits already pushed to a shared branch
+
+If the working tree needs a clean state, the **only** correct sequence is:
+
+    git fetch origin
+    git reset --hard origin/main
+    git clean -fd
+
+This applies equally to humans, local Claude Code, cloud Claude agents, Codex,
+and any other agent. The "Initial commit — fresh start for AI workflow" pattern
+that appeared independently on origin and local for three workspace repos is
+exactly what this rule prevents — it costs ~40 commits of redundant local work
+every time it happens.
+<!-- repos_sync:history:end -->