Add ~/.omp config; nvim git-repo external; ya pkg install hook

- dot_omp: agent config/keybindings/mcp/themes/commands + loop defs,
  goals, run-loop.sh; dotstate config.yml symlink materialized; dbs,
  logs, sessions, memories, blobs, caches, .env (secret), and
  managed-skills excluded
- .chezmoiexternal.toml: prdlk/nvim as git-repo external — no
  refreshPeriod + ff-only pull, local checkout wins over remote
- yazi plugins: vendored source copies dropped (target-ignored already);
  package.toml is the manifest, installed via run_onchange ya pkg
  install hook; stale piper/easyjump pins bumped to match live content
- herdr: plugins/github checkout, logs, session.json, .bak,
  release-notes dropped from sync (herdr-managed machine state)

run_onchange_after_install-yazi-plugins.sh.tmpl

@@ -0,0 +1,7 @@
+#!/bin/sh
+# Reinstall yazi plugins from the manifest whenever it changes.
+# package.toml hash: {{ include "dot_config/yazi/package.toml" | sha256sum }}
+set -eu
+command -v ya >/dev/null 2>&1 || exit 0
+[ -f "${XDG_CONFIG_HOME:-$HOME/.config}/yazi/package.toml" ] || exit 0
+ya pkg install