docs(widgets): contribute v0 draft pages for the 5 undocumented elements and the first Surface pages

[k08200]

Signaling before starting, given the redesign pre-work (#21).

Intent — contribute v0 widget draft pages per docs/widgets/TEMPLATE.md:

1. Elements currently in the catalog (base.toml v0.3.0) but undocumented: textfield, region, text, pager, video — implemented-vs-proposed claims labelled per the drafts/v0 rules, grounded in catalog + checker/core line references.
2. First Surface pages: sheet and dialog (default modality "sheet", reserved structural dismiss, focus-restoring dismiss descriptor, occlusion-by-modality — from uhura-check/lower.rs and uhura-core).

Questions

• Does this overlap with the redesign work in flight? Happy to hold or reshape.
• Contradiction to resolve for the video page: the catalog defines a full elements.video (base.toml:79-107), but the unknown-element notes say video is deferred to a poster-img + badge pattern (markup.rs). Which is current truth?

Docs-only; drafts remain disposable with v0 as documented.

[k08200]

Withdrawing the video question: #24 deletes both sides of the contradiction (the v0 catalog file and the stale steering note), so it is moot. The doc-contribution question is superseded by the 0.4 rewrite — see the note on #24; we'll handle #23's disposition ourselves.

[k08200]

Closing: both questions are resolved — the video contradiction is deleted by #24, and the v0 doc-contribution plan is superseded by the 0.4 rewrite (#23 closed accordingly; gap findings carried into the question on #24).