Link the Interplanetary Logistics transfer planner

[emptymalei]

Summary

The Interplanetary Logistics project is now a static web tool that finds the cheapest Earth to Mars transfer window and prices a shipment. It is live at https://interimm.org/interplanetary-logistics/ and already uses this site's header, footer and colours. This PR links to it from here.

• Announce it. Adds the tool as the newest activity in data/activities.yml (2026-10-01), in both languages. The newest activity drives the home page's "latest" banner, so it shows on / and /en/, and it appears on the Activities page.
• Menu. Adds a "Logistics" (English) / "星际物流" (Chinese) item to the More dropdown.
• Keep the old link working. The 2019 "Interplanetary Logistics API" entry pointed at the repository root. The static site replaces the Flask code there (pending the repo's PR add a toolbox page #3), so that entry now points at the python-api branch, which keeps the original code.

Checked

hugo --minify --gc with Hugo 0.135.0 (the CI version) builds cleanly. In the built output, both home pages show the new banner with the tool's link, the More menu has the new item in both languages, and the Activities timelines list the new entry first.

For review

• The Chinese wording is mine and should get a native read: the activity title "星际物流：地火转移窗口规划器", its description, and the menu label "星际物流".
• The tool page is English only. The Chinese entry says so (（页面为英文）) rather than pointing readers at a page they might not expect to be English.
• The menu item sits under More to keep the top bar uncluttered; it is easy to promote to a top-level item (drop parent: more and set a weight such as 35) if you prefer.
• Merging to hugo triggers the normal deploy workflow. The link to the tool works as soon as this lands; the tool itself is already published.

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