Refactor tenant-aware configuration system: remove tenant management code and associated templates

- Removed tenant configuration management code including TenantConfigManager and related functions.
- Deleted tenant resolver and guards for module access control.
- Eliminated tenant-aware error handling and associated HTML templates.
- Cleaned up main application file by removing tenant-related imports and context processors.
- Removed tenant configuration JSON file and related unit tests.

Co-authored-by: Copilot <copilot@github.com>

Website/main.py

@@ -1,4 +1,4 @@
-from flask import Flask, render_template, request, jsonify, flash, redirect, url_for, get_flashed_messages, session, send_file, after_this_request, g
+from flask import Flask, render_template, request, jsonify, flash, redirect, url_for, get_flashed_messages, session, send_file, after_this_request
 import os
 import json
 import atexit
@@ -22,12 +22,6 @@ from pymongo.errors import PyMongoError
 from bson.objectid import ObjectId
 import user as user_store
 
-# Tenant-aware configuration imports
-import tenant_resolver
-import tenant_config
-import tenant_guards
-import tenant_templates
-
 app = Flask(__name__)
 app.secret_key = "ASDfhbsdfseiufhgildsrfrjg874368546987s6e8468f4!?FAUS/&s"
 app.config["SESSION_COOKIE_HTTPONLY"] = True
@@ -36,45 +30,6 @@ app.config["SESSION_COOKIE_SECURE"] = os.environ.get("SESSION_COOKIE_SECURE", "0
 app.config["PREFERRED_URL_SCHEME"] = "https" if os.environ.get("SESSION_COOKIE_SECURE") == "1" else "http"
 
 
-# ============================================================================
-# TENANT-AWARE CONFIGURATION SETUP
-# ============================================================================
-
-# Register Jinja2 context processor for tenant-aware template helpers
-app.context_processor(tenant_templates.inject_tenant_context)
-
-
-@app.before_request
-def resolve_tenant_context():
-    """
-    Resolve the active tenant for the current request and store in g.
-    This runs before every request, making the tenant available to all handlers.
-    """
-    parent_domain = os.environ.get("INSTANCE_PARENT_DOMAIN", "meine-domain")
-    tenant_id = tenant_resolver.resolve_tenant(parent_domain)
-    g.tenant_id = tenant_id
-
-
-@app.errorhandler(403)
-def forbidden_error(error):
-    """
-    Custom error handler for 403 Forbidden responses.
-    Provides tenant-aware error messages for disabled modules.
-    """
-    if request.accept_mimetypes.best_match(['application/json', 'text/html']) == 'application/json':
-        return jsonify({
-            'error': 'Access denied',
-            'message': 'This resource is not available for your organization.'
-        }), 403
-    
-    return render_template('error_403.html', 
-                         tenant_id=g.get('tenant_id', 'default')), 403
-
-
-# ============================================================================
-
-
-
 @app.after_request
 def set_security_headers(response):
     response.headers["X-Content-Type-Options"] = "nosniff"