feat(web): add Eraser architecture diagram renderer

[guima-why]

Web architecture diagrams were limited to Mermaid and large diagrams were difficult to inspect. This adds a renderer setting under Settings > General, defaults architecture diagrams to the bundled Eraser renderer, and preserves Mermaid as an explicit choice and automatic fallback.

The change adds a versioned renderer-neutral DiagramGraph beside existing Mermaid sources, carries it through Web and A2A display events without breaking older payloads, and renders it locally in a sandboxed iframe with a deterministic Worker layout. It also adds the standalone ROS template preview page, adaptive diagram-panel width, the fixed 30-template visual corpus, complete zh/es/fr/de/ja/pt translations, and bundled Eraser/transitive license notices.

Validation:

• Full repository suite: 15,934 passed, 2 skipped
• Post-review i18n and Web regression suite: 341 passed
• Ruff and ty checks passed
• 30/30 representative ROS templates rendered successfully in browser evaluation
• Wheel contents verified to include the Eraser bundle, LICENSE, and NOTICE