Add Freshdesk proxy service for local Lambda development

[mbwatson]

This brings in a local development server for the Freshdesk Lambda function, making it possible to test and iterate on the proxy without redeploying to AWS.

Changes

• services/freshdesk/: New top-level directory for non-Node services, starting with this Freshdesk Lambda proxy
• handler.py: Lambda source of truth (moved from apps/)
• server.py: Local HTTP server wrapping the Lambda handler
• apps/site/: FAQ content loader updated to read FRESHDESK_PROXY_URL from .env, with a fallback to the production Lambda URL
• README.md: Setup, usage, and deployment notes.
• .gitignore: Added .env and .env.*

Notes

• The local proxy is only needed when developing the Lambda itself: normal site development uses the production Lambda URL by default.
• handler.py has no dependencies beyond the Python standard library; requirements.txt is only for the local dev server, and it's purely to support reading environment variables.

How to validate

• See new instructions in the README for config and starting the proxy server
• Start the proxy server
• Start the website dev server
  Because the FAQs content is fetched at build time we're looking for:
  1. [content] logs of success or failure, something like what's shown below, and
  2. if successful, FAQ content on the /resources/faqs page.

12:09:26 [content] Syncing content
[faqs] fetching from https://epxuifil2cc4sqfqws62zejcwi0cgfds.lambda-url.us-east-1.on.aws/faqs
12:09:26 [content] Synced content