Add Effect v4 support, Fast Refresh tooling, and revamped docs (#56)

## Summary

- Add `effect-fc-next`, a React 19 integration targeting Effect v4 beta.
- Introduce component lifecycles, scoped resources, queries, mutations, forms, lenses, views, and refreshable components.
- Add `@effect-view/vite-plugin` for Vite Fast Refresh support.
- Add an Effect v4 example application covering the new APIs.
- Expand test coverage for both the existing and next-generation packages.
- Replace the starter Docusaurus content with complete Effect View documentation while preserving the Effect v3 docs as a versioned snapshot.
- Update the landing page, navigation, package scripts, and build output.
- Extend CI with linting, tests, package builds, Docker builds, and container publishing.

## Validation

- `bun lint:tsc`
- `bun lint:biome`
- `bun test`
- `bun run build`
- `bun pack`
- Docker image build

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Co-authored-by: Julien Valverdé <julien.valverde@mailo.com>
Reviewed-on: Thilawyn/effect-fc#56

packages/example-next/.gitignore

@@ -0,0 +1,26 @@
+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+lerna-debug.log*
+
+node_modules
+dist
+dist-ssr
+*.local
+
+# Editor directories and files
+.vscode/*
+!.vscode/extensions.json
+.idea
+.DS_Store
+*.suo
+*.ntvs*
+*.njsproj
+*.sln
+*.sw?
+
+.tanstack