feat(devframe): add onServerError for post-bind server errors

startHttpAndWs's owned httpServer has no error listener once past the
bind window, so a later runtime error (e.g. a transient EMFILE while
accepting a connection) crashes the process. StartedServer exposes no
handle a caller could attach their own listener to either, unlike the
shared-server path where the caller already owns the object.

Add onServerError instead of exposing the raw httpServer — handing
out the raw object would let a caller call close() on it directly,
bypassing the wrapper's own close() and leaking the WS transport.

Attached only after the bind has already succeeded, so this never
touches bind-time crash/hang semantics — only what happens afterward.
No test: StartedServer deliberately doesn't expose the raw server, so
there's no way to trigger a genuine post-bind error through the
public API without a test-only seam.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Author: dvcolomban

packages/devframe/src/node/server.ts

@@ -110,6 +110,14 @@ export interface StartHttpAndWsOptions {
    * own startup banner. Devframe does not print one itself.
    */
   onReady?: (info: { origin: string, port: number, app: H3 }) => void | Promise<void>
+  /**
+   * Called for any error the owned HTTP server emits after it starts
+   * listening — e.g. a transient `EMFILE` while accepting a connection.
+   * Ignored when a `server` is supplied — the caller already owns that
+   * object and can listen on it directly. Without this, a post-bind error
+   * has no listener and crashes the process.
+   */
+  onServerError?: (error: Error) => void
 }
 
 export interface StartedServer {
@@ -258,6 +266,10 @@ export async function startHttpAndWs(options: StartHttpAndWsOptions): Promise<St
     await new Promise<void>((resolveListen) => {
       httpServer.listen(port, bindHost, () => resolveListen())
     })
+    // Attached only now that the bind has already succeeded — this never
+    // changes bind-time crash/hang semantics, only what happens afterward.
+    if (options.onServerError)
+      httpServer.on('error', options.onServerError)
   }
 
   const address = httpServer.address()