docs: record the stress findings and the 16-gate suite

caveats §13 documents the capacity ceiling the stress test found: the
workqueue backlog grows with the offered rate and OOM-panics a 1 GB guest
above ~1 Gbit/s. Gate count, suite status and the doc indexes move to
16/16 green.

docs/en/README.md

@@ -13,8 +13,9 @@ packet filter** to **Linux 7.3.4** — the real PF engine (`pf.c`, `pf_norm.c`,
 |---|---|
 | [guide.md](guide.md) | One-page architecture: components, data path, control plane, milestones |
 | [install.md](install.md) | Apply/build/install recipe (kernel, module, tools) |
+| [debian13.md](debian13.md) | Full from-zero implementation on Debian 13 (trixie): host prep, kernel/module/tools build, libvirt lab, stress test |
 | [build.md](build.md) | Build pipeline in detail: fetch → vendorize → kernel → module → pfctl |
-| [vm-lab.md](vm-lab.md) | The libvirt validation lab: topology, recreate/run, what each of the 15 gates proves |
+| [vm-lab.md](vm-lab.md) | The libvirt validation lab: topology, recreate/run, what each of the 16 gates proves |
 | [feature-matrix.md](feature-matrix.md) | Per-feature status: VERIFIED-in-VM / VERIFIED-offline / COMPILES-untested / NOT-ENABLED |
 | [pf-guide.md](pf-guide.md) | Daily use: what works today in `/etc/pf.conf`, and the deviations to know about |
 | [screencast.md](screencast.md) | The narrated videos (English and Portuguese): phases, pipeline, how to re-record |
@@ -38,4 +39,4 @@ Feature-status vocabulary used across these docs:
 - **NOT-ENABLED** — the code exists but the feature is off in this build.
 - **OUT-OF-SCOPE** — non-goal by design (spec §3).
 
-The lab suite is **15/15 green** (`./scripts/vm-run-tests.sh`).
+The lab suite is **16/16 green** (`./scripts/vm-run-tests.sh`).