fix(bankai): survive real-world CSS and serve real media types

Lightning CSS refuses IE-era hacks (*zoom and friends) that established
libraries like tachyons still carry; enable errorRecovery so bankai
strips them instead of failing the build — a zero-config tool ingesting
decade-old CSS should shrug, not crash. Found migrating an actual choo
v7 production site. Also: proper MIME types for avif/jpg/gif/mp4/woff in
the static server.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014NgfSjHE11oFpoSnLVKLXd

packages/bankai/lib/dev.js

@@ -16,6 +16,7 @@ export default async function dev ({ entry, port = 8080, title = 'choo' }) {
     appType: 'custom',
     server: { middlewareMode: true },
     plugins: [bankaiPlugin(entry, { css })],
+    css: { lightningcss: { errorRecovery: true } },
     logLevel: 'warn'
   })