Improve XSD visual layout and styling

[rg4444]

Motivation

• Improve the XSD diagram so it reads left→right (root left) with cleaner orthogonal routing and spacing to avoid cramped/incorrect edge elbows.
• Make node visuals more UI-friendly by using card-style nodes with a header, icon, and a visible attributes summary to resemble XMLSpy-like readability.
• Surface element/type attributes from the XSD so they can be displayed in the node cards.

Description

• Add AttributeDecl and GraphPoint types and extend ElementDecl, ComplexType, and GraphEdge to carry parsed attributes and routed points (web_src/js/features/xsdvisual/types.ts).
• Parse <xs:attribute> declarations with helpers getAttr and parseAttributes and attach attributes to inline complex types and element declarations (web_src/js/features/xsdvisual/parse.ts).
• Switch Dagre layout to left-to-right and increase spacing (rankdir: 'LR', nodesep, ranksep, marginx, marginy), increase NODE_HEIGHT, and attach routed points from the Dagre edge layout into GraphEdge.points using edge keys (web_src/js/features/xsdvisual/graph.ts).
• Render edges from routed Dagre points as polylines with improved stroke, rounded joins/caps, and marker coloring, and place labels at the routed midpoint (web_src/js/features/xsdvisual/render.ts).
• Render nodes as “cards” with a header strip, divider, icon, title alignment, and rows including type, base, occurs, and a truncated attributes summary; add an SVG drop-shadow filter and adjust node sizing (web_src/js/features/xsdvisual/render.ts).
• Increase diagram canvas size to 70vh for better fit (web_src/js/features/xsdvisual/ui.ts).
• Append XSD-specific CSS tokens and card styling to the repo file-view stylesheet to produce a clean, professional look (web_src/css/repo/file-view.css).

Testing

• Performed local code edits and added the changeset, then committed with the message Improve XSD visual layout and styling (commit succeeded).
• Attempted an automated Playwright screenshot run (mcp__browser_tools__run_playwright_script) to capture the updated renderer, but it failed to load the local dev server with net::ERR_EMPTY_RESPONSE, so no runtime screenshot was produced.
• No unit or integration tests were executed as part of this change (none run).

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Codex Task