fix: Recognize 301/401/403 as reachable in embedding health check

Remote APIs like Cloudflare Workers AI return 401 on /health and
301 on HEAD requests. These indicate the server IS reachable,
not down. Previously only 404/405 were treated as reachable,
causing all KB indexing to fail with 'Embedding server not available'.

botserver/src/core/kb/embedding_generator.rs

@@ -341,6 +341,12 @@ impl KbEmbeddingGenerator {
                         false
                     }
                 }
+            } else if status.is_redirection() || status.as_u16() == 401 || status.as_u16() == 403 {
+                // Redirect (301/302) or auth-required (401/403) means the server IS reachable
+                // This is typical for remote APIs like Cloudflare Workers AI
+                info!("Embedding server reachable at {} (status {} indicates external API), marking as ready", base_url, status);
+                set_embedding_server_ready(true);
+                true
             } else {
                 warn!("Embedding server health check returned status {}", status);
                 set_embedding_server_ready(false);