docs: scrub PII/IPs from gpu-bakeoff

- Rename host alias matt-strix -> strix-halo (removes third-party name)
- Move host URLs to env-var lookup (OLLAMA_*_URL), drop hardcoded IPs
  from harness source. Defaults: steel141 keeps localhost; pve197 and
  strix-halo require their env var to be set before use.
- Update doc: remove the Tailscale IP and LAN-IP references, describe
  access paths without specific addresses.
- Rename runs/matt-strix -> runs/strix-halo and patch the host field
  in each JSON.

Harness still functional for the original author (set the env vars)
and safe to share without leaking routable addresses.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scripts/gpu-bakeoff/runs/strix-halo/gemma4-26b-q8/long.json

@@ -1,5 +1,5 @@
 {
-  "host": "matt-strix",
+  "host": "strix-halo",
   "model_alias": "gemma4:26b-q8",
   "skipped": "model not available on host"
 }

scripts/gpu-bakeoff/runs/strix-halo/gemma4-26b-q8/short.json

@@ -1,5 +1,5 @@
 {
-  "host": "matt-strix",
+  "host": "strix-halo",
   "model_alias": "gemma4:26b-q8",
   "skipped": "model not available on host"
 }

scripts/gpu-bakeoff/runs/strix-halo/gemma4-26b/long.json

@@ -1,5 +1,5 @@
 {
-  "host": "matt-strix",
+  "host": "strix-halo",
   "gpu": "AMD Strix Halo iGPU",
   "vram_gb": null,
   "model_alias": "gemma4:26b",

scripts/gpu-bakeoff/runs/strix-halo/gemma4-26b/short.json

@@ -1,5 +1,5 @@
 {
-  "host": "matt-strix",
+  "host": "strix-halo",
   "gpu": "AMD Strix Halo iGPU",
   "vram_gb": null,
   "model_alias": "gemma4:26b",

scripts/gpu-bakeoff/runs/strix-halo/gemma4-31b/long.json

@@ -1,5 +1,5 @@
 {
-  "host": "matt-strix",
+  "host": "strix-halo",
   "gpu": "AMD Strix Halo iGPU",
   "vram_gb": null,
   "model_alias": "gemma4:31b",

scripts/gpu-bakeoff/runs/strix-halo/gemma4-31b/short.json

@@ -1,5 +1,5 @@
 {
-  "host": "matt-strix",
+  "host": "strix-halo",
   "gpu": "AMD Strix Halo iGPU",
   "vram_gb": null,
   "model_alias": "gemma4:31b",