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/grab-dist-dir.js

@@ -0,0 +1,51 @@
+import path from "path";
+import AppNames from "./grab-app-names";
+/**
+ * Env var holding the dist directory. The CLI sets it from `--dist-dir` or
+ * `dist_dir` in bunext.config.ts before any other module loads: most
+ * modules read the directory names once, at import time. Child processes
+ * (dev/start servers) inherit it.
+ */
+export const DistDirEnvName = "BUNEXT_DIST_DIR";
+const ReservedDirs = ["src", "public", "node_modules"];
+/**
+ * # Resolve the dist directory
+ * Returns the absolute path of the build artifact directory. `dist_dir` is
+ * relative to the project root (or absolute) and must sit inside it: the
+ * dev watcher only watches the project root, and checks it is alive through
+ * a probe file in the dist directory. Its relative path is also the URL
+ * path of the client bundles, so it is limited to URL-safe characters.
+ */
+export function resolveDistDir({ dist_dir, root_dir }) {
+    const resolved = path.resolve(root_dir, dist_dir?.trim() || AppNames.defaultDistDir);
+    if (!isInsideDir(resolved, root_dir)) {
+        throw new Error(`Invalid dist directory \`${dist_dir}\`: it must be a directory ` +
+            `inside the project root (${root_dir}).`);
+    }
+    const url_path = path
+        .relative(root_dir, resolved)
+        .split(path.sep)
+        .join("/");
+    if (!/^[\w.\-\/]+$/.test(url_path)) {
+        throw new Error(`Invalid dist directory \`${dist_dir}\`: use only letters, ` +
+            `digits, \`.\`, \`_\`, \`-\` and \`/\`.`);
+    }
+    for (const reserved of ReservedDirs) {
+        const reserved_dir = path.join(root_dir, reserved);
+        if (resolved === reserved_dir || isInsideDir(resolved, reserved_dir)) {
+            throw new Error(`Invalid dist directory \`${dist_dir}\`: it can't be ` +
+                `\`${reserved}/\` or inside it.`);
+        }
+    }
+    return resolved;
+}
+/**
+ * Whether `target` is strictly inside `dir` (not `dir` itself)
+ */
+function isInsideDir(target, dir) {
+    const relative = path.relative(dir, target);
+    return (Boolean(relative) &&
+        relative !== ".." &&
+        !relative.startsWith(`..${path.sep}`) &&
+        !path.isAbsolute(relative));
+}