feat(help): restructure /help as user-facing Help Center with Zammad integration

- Replace MkDocs redirect with a branded, SEO-optimised Help Center template
- Add sections: Quick Start, Sources, Destinations, Workflows, FAQ, Support
- Integrate optional Zammad live-chat widget and ticket form
- Add config settings: ZAMMAD_URL, ZAMMAD_CHAT_ENABLED, ZAMMAD_CHAT_ID,
  ZAMMAD_FORM_ENABLED, SUPPORT_EMAIL
- Move MkDocs developer docs from /help to /developer-docs
- Move interactive API docs (Swagger/ReDoc) to /admin/api-docs and /admin/api-redoc
- Add API Docs and Developer Docs links to Admin menu (desktop + mobile)
- Update navigation Help link from /help/ to /help
- Update .env.demo with Zammad configuration examples
- Document new settings in docs/ConfigurationGuide.md
- Rewrite tests to cover new Help Center behaviour

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

app/views/help.py

@@ -1,27 +1,42 @@
 """
-Help documentation view routes.
+Help Center view routes.
 
-Serves the built MkDocs documentation site at /help.
-The static site is built during the Docker image build and placed at docs_build/.
+Renders a user-facing, SEO-optimised Help Center page at ``/help``.
+The page is designed for SaaS end-users and includes guidance on
+features, integrations, workflows, and optional Zammad support widgets
+(live-chat and feedback form).
+
+The developer-oriented MkDocs documentation is served separately at
+``/docs`` and is intentionally **not** cross-linked from this page.
 """
 
 import logging
 import pathlib
 
 from fastapi import Request
-from fastapi.responses import RedirectResponse
 
-from app.views.base import APIRouter
+from app.config import settings
+from app.views.base import APIRouter, templates
 
 logger = logging.getLogger(__name__)
 
 router = APIRouter()
 
-# Path to the built MkDocs documentation
+# Path to the built MkDocs documentation (kept for reference / backwards compat)
 _DOCS_BUILD_DIR = pathlib.Path(__file__).parents[2] / "docs_build"
 
 
 @router.get("/help", include_in_schema=False)
-async def help_redirect(request: Request) -> RedirectResponse:
-    """Redirect /help to /help/ so the MkDocs index is served correctly."""
-    return RedirectResponse(url="/help/", status_code=301)
+async def help_center(request: Request):
+    """Render the end-user Help Center page."""
+    return templates.TemplateResponse(
+        "help.html",
+        {
+            "request": request,
+            "zammad_url": settings.zammad_url,
+            "zammad_chat_enabled": settings.zammad_chat_enabled,
+            "zammad_chat_id": settings.zammad_chat_id,
+            "zammad_form_enabled": settings.zammad_form_enabled,
+            "support_email": settings.support_email,
+        },
+    )