set up native plugins wiring

[jschwarz2030]

• Added native plugin system: plugins are IIFE bundles loaded at runtime via VITE_DEPLOYMENT_PLUGIN_URLS
• Exposed host React, ReactDOM, and jsx-runtime on window before app boot so plugins share a single React instance
• Extended PluginApiContext with theme, user, navigate, and ui (Button, Label, Textarea) so plugins can use host components
• Added TaskActionExtension and TaskActionPanelExtension types for plugins to inject UI into the task action modal and task footer
• Wired extensions into TaskActionModal and TaskPanel with replace/append slot support
• Updated plugin security to allow same-origin plugin URLs without allowlist checks
• Added catch-all route guard (isCoreAppPath) so plugin routes don't interfere with core routes
• Loosened task search schema to pass arbitrary query params through to plugins
• Added Vite plugin middleware to serve /plugins/ bundles in dev and preview
• Added env.json runtime config support via runtimeEnv() Vite plugin