Overhaul SSR caching, dev hot-reload, and server memory footprint

[Uttkarsh-Srivastava]

Summary

• ChunkExtractor caching (production) — ChunkExtractor instances are now cached per route instead of being created on every request. loadable-stats.json is also parsed once and held in memory, eliminating repeated disk reads.
• Simplified asset extraction — extract.js refactored to derive CSS and preload JS links directly from the cached ChunkExtractor instance, removing the separate routeCssCache and preloadJSLinkCache maps.
• SSR compiler removed from dev client process — The SSR webpack watcher that ran in the same process as the client dev server has been removed. SSR now runs in a separate process, reducing peak memory usage during development.
• Webpack filesystem cache (dev) — Enabled webpack filesystem cache in development mode (written to node_modules/catalyst-core/.cache/webpack), reducing rebuild memory pressure and speeding up incremental builds.
• Hot-reload overhaul — Replaced --watch-path flags with a chokidar watcher inside startServer.js that watches the app's /server directory. On change, require cache is cleared (clearServerCache) and the server restarts cleanly.
• Fixed EADDRINUSE race condition — restartServer() now nulls serverInstance before calling close(), preventing concurrent watcher events from each scheduling an independent startServer() callback on the same closing socket.
• Port availability pre-check — Both the Node server and the webpack dev server now probe their target port with a temporary TCP server before binding, surfacing a clear error instead of a cryptic EADDRINUSE.
• Unified handler for dev and prod — Removed the separate handler.development.js SSR bundle. Both environments now use the same handler.js entrypoint.
• cleanCache CLI command — New catalyst cleanCache command removes the webpack filesystem cache and loadable-stats.json, forcing a full rebuild on next dev start.
• Body parser size limits — JSON and raw body parsers capped at 100kb to prevent oversized payloads from inflating heap usage.
• eval-cheap-module-source-map devtool — Switched from inline-source-map (embeds full source maps in bundles) to eval-cheap-module-source-map for faster builds and lower memory footprint in dev.
• React Refresh babel plugin — Added react-refresh/babel to the development Babel env for proper fast-refresh support.
• Removed css-hot-loader — Dropped the old CSS hot loader; CSS updates are now handled through React Refresh and the webpack dev server HMR pipeline.

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