docs: Linux-guest benchmark (RUNBOOK §10) + Windows-host benchmark plan

§10: single-job Measure-CIBenchmark on LinuxBuild2404 (DHCP, 10 iter) on the
Linux host — boot total 8.82s avg, near-deterministic even on DHCP (IP-acquire
7.45s, σ≈0.01). Guest-vs-guest table: Linux guest ~63% faster boot total than
the Windows static-IP guest (§8) on the same host.

plans/benchmark-windows-host.md: dual-boot plan to collect the symmetric
Windows-host numbers (§11 Win static, §12 Linux DHCP, §13 concurrent burn-in)
so the host×guest×IP-mode matrix is complete and Linux-vs-Windows is a
column-for-column comparison. Includes Windows paths, Credential Manager
prereqs, and the BaseClean-Linux snapshot caveat.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/RUNBOOK.md

@@ -503,3 +503,39 @@ sudo -u ci-runner /opt/ci/venv/bin/python -c \
 
 See `TODO.md` (IP-pool auto-reconciliation) for the proposed fix.
 
+---
+
+## 10. Linux guest single-job baseline — LinuxBuild2404 (B7 follow-up)
+
+Recorded 2026-06-07 — `Measure-CIBenchmark.ps1 -GuestOS Linux -Iterations 10`,
+Linux Mint host + VMware Workstation Pro Linux, run as `ci-runner`, template
+`LinuxBuild2404` / snapshot `BaseClean-Linux`, **DHCP** (no static IP — the
+guest reads its DHCP lease and publishes it via `guestinfo.ci-ip`; the
+Windows-only `ci-static-ip.ps1` task does not apply). Ready = SSH/22 probe.
+
+| Iter    | Clone (s) | Start (s) | IP acquire (s) | Ready (s) | Destroy (s) | Boot total (s) |
+| ------- | --------- | --------- | -------------- | --------- | ----------- | -------------- |
+| 1–10    | 0.22      | 1.14–1.16 | 7.44–7.48      | 0.00–0.01 | 4.90–4.99   | 8.80–8.86      |
+| **avg** | **0.22**  | **1.14**  | **7.45**       | **0.00**  | **4.94**    | **8.82**       |
+
+**Key finding**: the Linux guest is near-deterministic *even on DHCP*
+(σ ≈ 0.01 s on IP-acquire) — no static-IP injection needed. IP-acquire is
+7.45 s vs Windows-guest 58 s (DHCP, §6) / 21.8 s (static, §8). Boot total
+8.82 s — ~2.7× faster than the Windows static-IP guest.
+
+**Guest-vs-guest comparison (Linux host, single-job):**
+
+| Metric     | Win guest static (§8) | Lin guest DHCP (§10) | Lin advantage |
+| ---------- | --------------------- | -------------------- | ------------- |
+| Clone      | 0.40 s                | 0.22 s               | −45%          |
+| Start      | 1.88 s                | 1.14 s               | −39%          |
+| IP acquire | 21.77 s               | 7.45 s               | **−66%**      |
+| Ready      | 0.00 s                | 0.00 s               | ≈ same        |
+| Destroy    | 10.40 s               | 4.94 s               | −53%          |
+| Boot total | 24.05 s               | 8.82 s               | **−63%**      |
+
+Caveat: different IP modes (Win static-IP task vs Lin DHCP+guestinfo) — the
+comparison reflects the *as-deployed* path for each guest, not an
+IP-mode-controlled A/B. The Win guest's static-IP floor (~21.8 s) is dominated
+by Windows boot + Task Scheduler + NIC reconfig; the Linux guest needs no such
+in-guest agent.