Docs: Update use-media Reference Page for MediaHost Architecture

[decepulis]

The use-media reference page at site/src/content/docs/reference/use-media.mdx still says Player.useMedia "returns the current HTMLMediaElement". That hasn't been true since #1334 refactored the Media interface for the MediaHost architecture — the hook now returns a Media object, and the underlying DOM element is reached via media.target.

The Basic Usage demo was removed in #1109 because it accessed tagName, currentSrc, videoWidth, and videoHeight directly on the hook result, which no longer typecheck under the new Media shape.

Tasks

• Update the prose to accurately describe the new Media return type and the role of media.target for reaching the underlying DOM element.
• Author a new Basic Usage demo following the post-chore(site): rewrite media element builder for MediaHost architecture #1334 conventions (access DOM properties via media.target).

[github-actions]

Triage recommendations:

• Milestone: 26.2 — the reference page has been inaccurate since the MediaHost architecture landed; fixing it in the current cycle keeps docs aligned with shipped behavior.
• Priority: P2 — docs regression (not a runtime break, but misleads anyone reading the reference page).
• Epic / related planning: This fits alongside the broader API reference coverage work tracked in Docs: API Reference Pages for Media Elements #727 and its child Docs: Media Element API Reference Pages #1253 (Media Element API Reference Pages). Consider grouping with those in the Post-Beta epic (Chore: Post-Beta #919) for roadmap visibility.
• Related issues to plan alongside: Docs: Triage Undocumented Public Utils #1183 (Docs: Triage Undocumented Public Utils) and Docs: Add API Reference Page for useContainer #1184 (Docs: Add API Reference Page for useContainer) are similar hook/util reference gaps that could be batched.
• No blocked-by relationships — this is self-contained and can proceed independently.