Add ACCI crash context map

[cryptokoh]

What changed

• Add ACCI, a standalone WebGL visualization of Austin Vision Zero crash data
• Add severity-weighted spatial columns, crash markers, year and mode filters, terrain, ranked hotspots, and random targeting
• Add Austin address search, nearby crash summaries, and double-click pin lookup
• Add accessible mobile bottom sheets, exclusive overlay behavior, larger crash tap targets, and a bottom-left Explore Data control
• Add Netlify configuration, security headers, deployment documentation, and a project handoff

Why

Crash data is difficult to understand as a spreadsheet. ACCI presents serious harm spatially while preserving access to individual source records and clear data limitations.

User impact

Visitors can explore recent fatal and suspected serious-injury crashes across Austin, investigate an address or surrounding area, browse top concentrations, and inspect individual crash details on desktop or mobile.

Validation

• node --check accispace/app.js
• npx --yes html-validate@10 accispace/index.html
• git diff --check -- accispace
• Browser verification at 390 by 844 pixels
• Real crash-marker pointer selection
• Exclusive mobile overlay checks
• Production verification at https://acci.handprotocol.org
• 2,063 live crash records loaded without browser exceptions

[netlify]

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