[Li-T-1025]

• Tianditu vector (vec_w), imagery (img_w) and hybrid basemaps, each with its own WMTS annotation overlay (cva_w / cia_w) drawn the same way the Dark style draws labels
• Key is stored through the existing encrypted api-keys store; keyless requests serve blank tiles instead of failing
• Settings > Maps: Tianditu key row next to the OpenAIP and CARTO rows, reusing ApiKeyInput
• Tile requests carry a browser User-Agent, because console keys default to the browser-side type (301012); a rejected key is logged once per layer instead of failing silently
• i18n for en/de/zh-CN/zh-TW/uk, wiki notes, unit tests for the WMTS URL and attribution

[rubenCodeforges]

Hi, thanks for the work on this, it's clean and well documented, and I understand Tianditu is the basemap that is actually reachable in China.

I won't merge it into core though. ArduDeck core stays provider-neutral, and three China-only layers would appear in every user's layer picker worldwide. Provider integrations like this belong in a cargo (ArduDeck's module system), so the people who need it can install it and everyone else never sees it.

If you'd like it, please open a cargo request issue for Tianditu basemaps and we'll build it as a cargo.

One note for that: please don't rely on faking a browser User-Agent to get around the browser-side key type. The cargo should use a server-side key, and the setup notes should explain how to create one in the Tianditu console.

I'll close this PR for now. Thanks again!