refactor: rename the application package to docsgpt

The backend import package is now docsgpt, the name it will carry on PyPI;
application was far too generic to install into anyone's site-packages.
git mv plus a mechanical rewrite of every import, dotted string and path
reference: 734 Python files, the compose files, Dockerfile, workflows, docs,
setup scripts, devcontainer, k8s manifests, vscode config, pytest and coverage
config, .gitignore. Behaviour is unchanged.

Kept for one release:
- A top-level application package whose meta-path finder resolves
  application.x.y to the already-imported docsgpt.x.y object, so old imports
  and entry points (celery -A application.app.celery,
  uvicorn application.asgi:asgi_app) keep working with a FutureWarning.
- Celery registers every application.* task name as an alias of its
  docsgpt.* task on start-up, so messages queued by the previous release still
  run. The redbeat key prefix moves to redbeat:docsgpt:v2: so schedule entries
  the previous release wrote are left unread instead of firing twice.

The backend image builds from the repository root (docker build -f
docsgpt/Dockerfile .) so it can ship the alias package; a root .dockerignore
allow-lists docsgpt/ and application/ and keeps caches, local data, .env
files, the sample index files and the Dockerfile out. Compose and the image
workflows point at the new context.

docsgpt/parser/remote/sitemap_loader.py

@@ -0,0 +1,111 @@
+import logging
+import re
+
+import defusedxml.ElementTree as ET
+from bs4 import BeautifulSoup
+
+from docsgpt.parser.remote.base import BaseRemote
+from docsgpt.parser.schema.base import Document
+from docsgpt.core.url_validation import validate_url, SSRFError
+from docsgpt.security.safe_url import UnsafeUserUrlError, pinned_request
+
+class SitemapLoader(BaseRemote):
+    def __init__(self, limit=20):
+        self.limit = limit  # Adding limit to control the number of URLs to process
+
+    def load_data(self, inputs):
+        sitemap_url= inputs
+        # Check if the input is a list and if it is, use the first element
+        if isinstance(sitemap_url, list) and sitemap_url:
+            sitemap_url = sitemap_url[0]
+
+        # Validate URL to prevent SSRF attacks
+        try:
+            sitemap_url = validate_url(sitemap_url)
+        except SSRFError as e:
+            logging.error(f"URL validation failed: {e}")
+            return []
+
+        urls = self._extract_urls(sitemap_url)
+        if not urls:
+            print(f"No URLs found in the sitemap: {sitemap_url}")
+            return []
+
+        # Load content of extracted URLs
+        documents = []
+        processed_urls = 0  # Counter for processed URLs
+        for url in urls:
+            if self.limit is not None and processed_urls >= self.limit:
+                break  # Stop processing if the limit is reached
+
+            try:
+                url = validate_url(url)
+            except SSRFError as e:
+                logging.error(f"URL validation failed for sitemap entry {url}: {e}")
+                continue
+            try:
+                response = pinned_request("GET", url, timeout=30)
+                response.raise_for_status()
+                soup = BeautifulSoup(response.text, "html.parser")
+                documents.append(
+                    Document(
+                        soup.get_text(separator="\n", strip=True),
+                        extra_info={"source": url},
+                    )
+                )
+                processed_urls += 1  # Increment the counter after processing each URL
+            except Exception as e:
+                logging.error(f"Error processing URL {url}: {e}", exc_info=True)
+                continue
+
+        return documents
+
+    def _extract_urls(self, sitemap_url):
+        try:
+            response = pinned_request("GET", sitemap_url, timeout=30)
+            response.raise_for_status()
+        except UnsafeUserUrlError as e:
+            print(f"URL validation failed for sitemap: {sitemap_url}. Error: {e}")
+            return []
+        except Exception as e:
+            print(f"Failed to fetch sitemap: {sitemap_url}. Error: {e}")
+            return []
+
+        # Determine if this is a sitemap or a URL
+        if self._is_sitemap(response):
+            # It's a sitemap, so parse it and extract URLs
+            return self._parse_sitemap(response.content)
+        else:
+            # It's not a sitemap, return the URL itself
+            return [sitemap_url]
+
+    def _is_sitemap(self, response):
+        content_type = response.headers.get('Content-Type', '')
+        if 'xml' in content_type or response.url.endswith('.xml'):
+            return True
+
+        if '<sitemapindex' in response.text or '<urlset' in response.text:
+            return True
+
+        return False
+
+    def _parse_sitemap(self, sitemap_content):
+        # Remove namespaces
+        sitemap_content = re.sub(' xmlns="[^"]+"', '', sitemap_content.decode('utf-8'), count=1)
+
+        root = ET.fromstring(sitemap_content)
+
+        urls = []
+        for loc in root.findall('.//url/loc'):
+            if not loc.text:
+                continue
+            urls.append(loc.text)
+
+        # Check for nested sitemaps
+        for sitemap in root.findall('.//sitemap/loc'):
+            nested_sitemap_url = sitemap.text
+            if not nested_sitemap_url:
+                continue
+            urls.extend(self._extract_urls(nested_sitemap_url))
+
+        return urls