#7434: docs: add .mailmap to restore author attribution

This PR adds a `.mailmap` file to correctly attribute commits made by contributor `WeatherPal-AI` that were inadvertently authored with a local system email (`ubuntu@...`). **Verification:** The following merged commits belong to `WeatherPal-AI`: - `7c96bde3b` (docs: fix GitHub branding capitalization) - `49a3e3795` (docs: fix missing apostrophes in FAQ headers) - `23f0efbf0` (docs: use straight quotes for code terms) This mapping ensures proper credit in the contribution graph. Contributor `@WeatherPal-AI` can confirm. <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> Adds a repository-level `.mailmap` entry so commits authored as `Ubuntu <ubuntu@…compute.internal>` are attributed to the GitHub noreply identity for `WeatherPal-AI`. This improves contributor attribution in `git shortlog`, blame views, and tooling that honors `.mailmap`, without affecting runtime code. <h3>Confidence Score: 4/5</h3> - This PR is safe to merge; it only adds a `.mailmap` entry for attribution. - Change is documentation/metadata-only and does not affect runtime behavior. Main risk is minor: `.mailmap` formatting/order conventions and ensuring it maps the intended identities. - `.mailmap` (validate mapping format and newline). <!-- greptile_other_comments_section --> _{(3/5) Reply to the agent's comments like "Can you suggest a fix for this @greptileai?" or ask follow-up questions!} <!-- /greptile_comment -->