fix: resolve 6 production Sentry errors

- Prevent @fastify/static double-registration crash via decorateReply guard
- Fix non-ASCII filename header encoding (X-Output-Filename + RFC 5987 Content-Disposition)
- Add EACCES error handling to all startup mkdir calls with actionable messages
- Add WAL autocheckpoint and journal size limit to prevent unbounded SQLite growth
- Fix Python sidecar EPIPE handling to reject pending requests and trigger restart
- Ensure Docker entrypoint creates all subdirectories before chown

packages/ai/src/bridge.ts

@@ -153,7 +153,20 @@ function startDispatcher(): ChildProcess | null {
       env: buildMinimalEnv(),
     });
 
-    child.stdin?.on("error", () => {});
+    child.stdin?.on("error", (err: NodeJS.ErrnoException) => {
+      if (err.code === "EPIPE" || err.code === "ERR_STREAM_DESTROYED") {
+        console.error(
+          `[bridge] Dispatcher stdin pipe broken (${err.code}), rejecting pending requests`,
+        );
+        for (const [id, req] of pendingRequests.entries()) {
+          req.reject(new Error("Python dispatcher stdin closed unexpectedly"));
+          pendingRequests.delete(id);
+        }
+        recordCrash();
+        dispatcher = null;
+        dispatcherReady = false;
+      }
+    });
 
     let stderrBuffer = "";