test(web): drop sidebar artwork styling snapshots

[juliusmarminge]

The sidebar artwork tests asserted literal focus-ring classes, theme token strings, and SVG crop coordinates. Remove those implementation snapshots without changing production artwork.

Keep enabled/disabled artwork and supported environment-label coverage. Keep both repeated-render SVG ID collision tests, since duplicate definition IDs can break multiple artwork instances.

Verification: all four remaining SidebarStageBackdrop tests pass. Production code and visuals are unchanged.

Model: gpt-6 astra. Harness: Codex in T3 Code.

Note

Remove SidebarStageBackdrop styling snapshots and artwork assertions

Deletes three tests from the SidebarStageBackdrop suite that asserted focus-ring offset classes, theme-owned color tokens, and compact crop viewBox values for nightly and dev variants. The suite still tests environment-to-artwork resolution, supported labels, and SVG definition ID uniqueness.

^{Macroscope summarized 03f36e1.}

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	13.5 KiB	13.6 KiB	+67 B (+0.5%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.0 KiB	7.0 KiB	+9 B (+0.1%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.5 KiB	6.6 KiB	+58 B (+0.9%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	57.0 KiB	57.1 KiB	+88 B (+0.2%)	66.4 KiB	✅
Codex	Live turn messages	8	10	+2 (+25.0%)	21	✅
Claude	Total thread wire	13.6 KiB	13.5 KiB	−24 B (−0.2%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.0 KiB	7.0 KiB	0 B (0.0%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.5 KiB	6.5 KiB	−24 B (−0.4%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	57.8 KiB	57.8 KiB	−44 B (−0.1%)	66.4 KiB	✅
Claude	Live turn messages	9	8	−1 (−11.1%)	21	✅

Baseline: 761d4ba · PR result: 03f36e1 · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 113.8 KiB
• Claude decoded thread snapshot: 114.5 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.