feat: add Tally integration

[pranavrajs]

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

Tools

• List Forms (list_forms, GET)
• Get Form (get_form, GET)
• List Form Questions (list_form_questions, GET)
• List Submissions (list_submissions, GET)
• List Submissions by Date (list_submissions_by_date, GET)
• Get Submission (get_submission, GET)

Testing

• The manifest passes the validator ("valid": true).
• Every template was rendered locally with Liquid 5.4.0 against sample responses built from Tally'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.

Review notes

• Tally has no way to search submissions by person; Captain reads the listed answers to match an email or name.
• No tally-version header is pinned.

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.