Add .htaccess file to rewrite URLs correctly

.htaccess

@@ -0,0 +1,47 @@
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to you under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+###################################################################
+# NOTE This file is not automatically copied from the main branch to
+# the asf-site (publishing) branch, so if you make changes to this
+# file you need to move them manually to the asf-site branch
+###################################################################
+
+# redirect urls to the output directory
+# See https://issues.apache.org/jira/browse/INFRA-27512
+RewriteEngine On
+
+# Two-step flow:
+# 1) Normalize extensionless URLs to a trailing slash.
+# 2) Internally rewrite all non-output requests into output/.
+
+# Redirect extensionless, non-output URLs to the trailing-slash form
+# (example: /blog/2025/12/15/post -> /blog/2025/12/15/post/).
+RewriteCond %{ENV:REDIRECT_STATUS} ^$
+# Use THE_REQUEST so the original URL is honored even if server rewrites to /output/.
+RewriteCond %{THE_REQUEST} \s+(/[^\s?]+) [NC]
+# Skip URLs already targeting output (example: /blog/output/...).
+RewriteCond %1 !/output/
+# Skip URLs that already end with a slash (example: /blog/2025/12/15/post/).
+RewriteCond %1 !/$
+# Skip URLs that look like files (have an extension) (example: /blog/theme/css/style.css).
+RewriteCond %1 !\.[^./]+$
+RewriteRule ^.*$ %1/ [R=301,L]
+
+# Rewrite all non-output requests to the Pelican output/ directory
+# (example: /blog/2025/12/15/post/ -> /blog/output/2025/12/15/post/).
+RewriteCond %{ENV:REDIRECT_STATUS} ^$
+RewriteCond %{REQUEST_URI} !/output/
+RewriteRule ^(.*)$ output/$1 [L]