feat: add Typeform integration

[pranavrajs]

Adds the Typeform integration (Others). Find Typeform forms and look up what a customer submitted.

Tools

• List Forms (list_forms, GET)
• Get Form (get_form, GET)
• Search Responses (search_responses, GET)
• List Responses (list_responses, GET)
• Get Response (get_response, GET)

Testing

• The manifest passes the validator ("valid": true).
• Every template was rendered locally with Liquid 5.4.0 against sample responses built from Typeform's API docs.
• Not run against the live API. No credentials were available, so tool-tester.rb has not been run with a real key. This needs doing before merge.
• No logo is included.

The root README.md row and .env.example entry for this integration are in a separate PR, so the per-integration PRs do not conflict with each other.