1.4.0: not_found, server-only response options, compression

- Server functions can return not_found: true to render the 404 page
  with status 404.
- Page components and window.__PAGE_PROPS__ (and HMR updates) only get
  props, query, url and error. response_options, redirect, cache settings
  and res_transform stay on the server, so cookies and private headers no
  longer end up in the HTML. BunextPageProps is narrowed to match
  (breaking for code that read server-only fields from component props).
- response_options headers go through a Headers object, so repeated
  headers such as several Set-Cookie survive.
- Redirects: status_code wins over permanent; response_options headers
  and res_transform apply to redirects too.
- Gzip for compressible text responses; compress: false to turn it off.
- Files the router matches but never bundles (.server.ts, __root,
  excluded paths and directories) return 404 instead of looping through
  dev rebuild retries.
- Missing public files return 404 rather than 403, so dotted page paths
  like /users/john.doe fall through to pages again.
- importFresh detects rewrites within the filesystem's mtime granularity.
- README: self-hosted React (not esm.sh), snake_case option names, static
  file serving, cache headers, the new options.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

dist/utils/not-found-error.d.ts

@@ -0,0 +1,9 @@
+/**
+ * Thrown to render the 404 page (with status 404) instead of the matched
+ * page: for unmatched or non-routable paths, and when a page's server
+ * function returns `not_found: true`.
+ */
+export default class NotFoundError extends Error {
+    status: number;
+    constructor(message: string);
+}