docs: collect data from 800+ websites with Teable AI

[Jocky-Teable]

Adds the September 17 announcement, "Collect data from 800+ websites with Teable AI", in all 11 documentation languages, with the supplied overview image and three demonstration videos. Updates localized documentation banners and fills the nine missing translations of both the September 15 and September 16 changelog entries.

Merges the latest main (5f28764) and resolves the overlapping changelog additions, preserving the original English and Chinese September 16 content and all historical entries. Entries appear in September 17, 16, 15 order across all 11 languages.

Validation: MDX compilation, content preservation and date ordering checks, all 18 September 16 items in every language, rendered localized titles and date anchors, desktop/mobile and LAN previews, and playback of the three demonstration videos. git diff --check passes.

[CLAassistant]

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