chore(agent): commit the machine tier and the doctrine text the checkout was already running

Landing blocker for #61 and #63: the deployment checkout is 12 commits behind and
`merge --ff-only` refuses while tracked paths are dirty. Discard is not available here
(workspace policy: no `checkout`/`stash` on shared state), so the dirt is committed.

- `agent/APPEND_SYSTEM.md`: the point-of-use / one-work-log / PR-link doctrine, already
  byte-identical to `origin/main` (`cmp` against the trunk blob: no difference). No new
  prose — the commit exists so the trunk merge can proceed.
- `agent/config.yml` and `agent/managed-skills/**`: the machine-live tier the heartbeat
  owns (AGENTS.md § Live-sync tiers).

`ALLOW_SECRETS=1` was used, deliberately and after auditing the staged diff by hand: the
only credential-shaped strings in it are two copies of `AKIA0000000000000EXAMPLE` — the
inert all-zero AWS example id — and they appear inside the two skill pages that teach
that exact placeholder shape. This checkout is still running the pre-#61 hook; the merged
gate (value-scoped placeholder filter, `71601f7`) exempts this value, so the refusal
dies with this landing. No `--no-verify` was used: the gate ran and its verdict is
recorded here.

Refs #61

agent/managed-skills/dotfiles-deployment-truth-audit/SKILL.md

@@ -0,0 +1,76 @@
+---
+name: dotfiles-deployment-truth-audit
+description: "Answer \"is my X config actually tracked and deployed?\" per package: classify every file by readlink, expose tracked-then-ignored debt, and re-derive census numbers from the command printed on the page."
+---
+
+Answer to "does this repo still track my <pkg> settings?" must be a measurement, never a remembered count. The tracked unit is the **file**, not the directory: a live directory can be a real directory and still be fully tracked, because every file inside it is a symlink into the repo.
+
+Run in the deployment checkout (the checkout IS the deployment).
+
+## 1. Tracked set, per package, both tiers
+
+```bash
+cd ~/.omp                      # or the repo that owns dotfiles/
+git ls-files dotfiles/<pkg>    # base tier
+git ls-files dotfiles/zz-$(hostname) | grep <pkg>   # host override tier — counted separately
+```
+
+The `zz-*` tier overrides base files by the same relative path, so a per-package count
+that ignores it under-reports what a machine actually runs.
+
+## 2. Live wiring — classify every tracked file (never by directory)
+
+```bash
+for f in $(git ls-files dotfiles/<pkg>); do
+  rel=${f#dotfiles/<pkg>/}; live="$HOME/$rel"
+  if [ -L "$live" ]; then printf 'link %-50s -> %s\n' "$rel" "$(readlink "$live")"
+  elif [ -e "$live" ]; then printf 'REAL %-50s (NOT a link)\n' "$rel"
+  else printf 'absent %s\n' "$rel"; fi
+done
+```
+
+- `REAL` = the repo copy is a fiction: live state diverged, deployment never reached it.
+- `absent` = tracked relic, nothing consumes it (candidate for `git rm --cached`).
+- Spaces in filenames break the `for` loop (`palettes/Gruber Red.json` splits into two
+  rows). Use `git ls-files -z | tr '\0' '\n'` + `while read -r` when names can hold spaces.
+- Reverse direction finds untracked-but-load-bearing files:
+  `find ~/.config/<pkg> -maxdepth 2 \( -type f -o -type l \) | while read -r p; do case "$(realpath "$p")" in $PWD/dotfiles/*) ;; *) echo "not from repo: $p";; esac; done`
+
+## 3. Live state that must stay untracked
+
+Generated palette output and app state are expansion, not authorship. Distinguish by
+mtime cluster, not by name: `find ~/.local/state/<app> -type f -printf '%TY-%Tm-%Td %p\n'` —
+a same-second mass write is a generator; single later re-stamps are re-runs. Pointers a
+switcher script writes (e.g. `cfg/display.kdl -> desk-1-home.kdl`) are machine state too.
+
+Then check the hazard this creates: grep the entrypoint for includes of those generated
+files. A **non-optional** include of a correctly-untracked generated file bricks a fresh
+box (`include "noctalia.kdl"` with no `optional=true` = niri cannot start until the theme
+pipeline has run once). Report it as a fresh-box failure, not a style note.
+
+## 4. Tracked-then-ignored debt (invisible to every normal check)
+
+```bash
+git ls-files dotfiles | grep AGENTTRASH         # trash committed inside the tree
+git check-ignore --no-index -v <that path>      # does an ignore rule match it?
+```
+
+`.gitignore` patterns without an interior slash (`.AGENTTRASH/`) match at **any depth**, so
+the rule was fine all along — the file simply entered history *before* the rule existed, and
+an ignore rule never reaches an already-tracked path. Only repair: `git rm --cached <path>`
+plus moving the working copy to the root `.AGENTTRASH/` (never `rm`). `git check-ignore`
+without `--no-index` prints nothing for tracked paths and reads as "not ignored" — that
+false negative is the trap.
+
+## 5. A census number is only valid with its command
+
+If a page prints a classifier command, every number on it must be reproducible by running
+that command. A row that the command does not reproduce was written from memory — wrong, not
+merely stale. Fix the row, and state the correction in the commit message rather than
+silently editing the number.
+
+## Verification before landing
+
+`bats tests/`, `scripts/kb-lint.sh omp-docs`, `scripts/kb-coverage.py omp-docs`, and
+`scripts/deploy.sh --check` **from the worktree** — `--check` is read-only; never run the
+real deploy from a worktree, it repoints live symlinks into the worktree the heartbeat reaps.