fix(docs): improve security and accessibility in help section

- Add aria-label to all Help nav links for better screen reader support
- Fix Samba config examples: use authenticated user instead of guest ok=yes
- Fix chmod 777 to chmod 770 with group-based access control
- Add security notes about dedicated groups and passwords in how-to guides
- Fix Python script to use os.environ.get() with explicit error messages
- Add app-specific password comment to EmailIngestion.md config example

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

frontend/templates/base.html

@@ -78,6 +78,7 @@
             </a>
             <a href="/help/"
                class="px-3 py-2 rounded-md text-sm font-medium text-gray-700 hover:text-gray-900 hover:bg-gray-100"
+               aria-label="Help and How-To Guides"
                title="Help &amp; How-To Guides"
                {% if request and request.url.path.startswith('/help') %}aria-current="page"{% endif %}>
               <i class="fas fa-circle-question mr-1 text-gray-400" aria-hidden="true"></i>Help
@@ -180,6 +181,7 @@
             <!-- Help documentation – visible to all users -->
             <a href="/help/"
                class="px-3 py-2 rounded-md text-sm font-medium text-gray-700 hover:text-gray-900 hover:bg-gray-100"
+               aria-label="Help and How-To Guides"
                title="Help &amp; How-To Guides"
                {% if request and request.url.path.startswith('/help') %}aria-current="page"{% endif %}>
               <i class="fas fa-circle-question mr-1 text-gray-400" aria-hidden="true"></i>Help
@@ -245,6 +247,7 @@
               </a>
               <a href="/help/"
                  class="block px-3 py-3 rounded-md text-base font-medium text-gray-700 hover:text-gray-900 hover:bg-gray-50"
+                 aria-label="Help and How-To Guides"
                  {% if request and request.url.path.startswith('/help') %}aria-current="page"{% endif %}>
                 <i class="fas fa-circle-question mr-2 text-gray-400" aria-hidden="true"></i>Help
               </a>
@@ -320,6 +323,7 @@
               <!-- Help documentation -->
               <a href="/help/"
                  class="block px-3 py-3 rounded-md text-base font-medium text-gray-700 hover:text-gray-900 hover:bg-gray-50"
+                 aria-label="Help and How-To Guides"
                  {% if request and request.url.path.startswith('/help') %}aria-current="page"{% endif %}>
                 <i class="fas fa-circle-question mr-2 text-gray-400" aria-hidden="true"></i>Help
               </a>