ci(n0): adopt Ubuntu-owned gate baselines

Adopt the complete review-only candidate from GitHub Actions run 29700301719, artifact 8446425713 (zip SHA-256 469e3fbf2a526611f61f1d43220dc966bcc414ba290595dd0e97d6b2f3fed978). The manifest records source ed0f310, ubuntu-24.04 x86_64, Rust 1.92.0, and skia-safe 0.93.1.

Captured essence: preserve all four named 1360x900 RGBA states, paired shot/timing ownership, same-host determinism, replay determinism, the ENG-0.2 differential, scene-cache equality, and the generous max(1.5x, +50us) timing rule. The candidate gate passed every portable check before installing and uploading exactly five files.

Etiology: the outgoing images came from 7c101b9 on aarch64-macos. Main commit abe0305 then deliberately changed the footer from the plan-code name anchor spike — E10 to n0_dev — anchor spike without updating the shots; that source change accounts for exactly 4,010 pixels in each current macOS render. Comparing current source across macOS and Ubuntu changes 2,627-3,992 pixels per shot (0.215-0.326%); visual diffs are confined to text rasterization, while geometry and colors align.

The timing numbers move from incomparable macOS measurements to CI-owned min-of-11 measurements: starter 15.639/1.654us and flat10k 1076.711/269.591us for resolve/build. This is an authority transfer, not a performance claim.

Deliberate drop: retire only aarch64-macos baseline authority and the stale E10 footer pixels. Preserve their provenance here and in #5/#44. format/grida.fbs, the published canvas-wasm freeze, probe-baseline.json, renderer behavior, and fixture content remain untouched.

Author: softmarshmallow

crates/n0/rig/baselines.json

@@ -1,14 +1,18 @@
 {
+  "ci_run_id": "29700301719",
   "entries": {
     "flat10k": {
-      "build_us": 82.5,
-      "resolve_us": 346.709
+      "build_us": 269.591,
+      "resolve_us": 1076.711
     },
     "starter": {
-      "build_us": 0.458,
-      "resolve_us": 7.25
+      "build_us": 1.654,
+      "resolve_us": 15.639000000000001
     }
   },
-  "machine": "aarch64-macos",
-  "note": "min-of-11 microseconds; regenerate with `gate --bless-bench`"
+  "host_id": "github-actions-ubuntu-24.04-x86_64",
+  "note": "CI-owned min-of-11 microseconds; regenerate shots and bench together after etiology",
+  "rust_toolchain": "1.92.0",
+  "skia_safe": "0.93.1",
+  "source_sha": "ed0f3109431587c99d25244542c89631060d8bdf"
 }