fix(api): improve error handling and add timeouts to edit_page endpoint

[Avalanche-ag]

Problem

The current /api/edit_page endpoint does not do input validation and assumes that targetUrl is always in the correct format. If it is malformed or missing, re.findall and the regex matcher crash the backend with an IndexError or TypeError. Furthermore, the requests library calls are made with no timeout, risking the server hanging indefinitely if the wikimedia API is temporarily unreachable.

Solution

This PR hardens the /api/edit_page code natively.

• Added strict presence and format validation to requestURL and content.
• Implemented timeout=10 on target API fetch and pushes.
• Handles missing token retrieval gracefully instead of unhandled downstream exceptions.

Related Tasks

Adresses the Backend Error Handling & Observability micro-task goals outline in T415715.