fix(marketing): make the Git illustration accessible

[rynfar]

The homepage Git illustration exposed three controls that look clickable but cannot perform an action. It now has one descriptive Pylon image label and excludes those decorative controls from keyboard navigation, while retaining its appearance and the surrounding explanation.

Selectively adopts pingdotgg/t3code#10130 (e5d086c262daab13a8adbb253e281c07ab235533) with Pylon product naming.

Validation: the marketing build and Astro check pass (12 files, zero errors, warnings or hints). A real browser confirms three interactive descendants before and zero afterward, the descriptive image label, and matching illustration bounds at 1180 × 900.

Before	After

Model: GPT-6 Astra. Harness: Codex.

[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	13.7 KiB	13.6 KiB	−5 B (−0.0%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.1 KiB	7.1 KiB	−4 B (−0.1%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.6 KiB	6.6 KiB	−1 B (−0.0%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	56.5 KiB	56.5 KiB	0 B (0.0%)	66.4 KiB	✅
Codex	Live turn messages	8	8	0 (0.0%)	21	✅
Claude	Total thread wire	13.6 KiB	13.8 KiB	+196 B (+1.4%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.1 KiB	7.1 KiB	0 B (0.0%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.5 KiB	6.7 KiB	+196 B (+2.9%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	57.3 KiB	58.2 KiB	+928 B (+1.6%)	66.4 KiB	✅
Claude	Live turn messages	7	9	+2 (+28.6%)	21	✅

Baseline: 983633a · PR result: 1317bfe · 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: 111.2 KiB
• Claude decoded thread snapshot: 111.9 KiB

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