docs(video-generation): rewrite around Steps, ParamField, AZ providers
The video-generation page was 454 lines with a 3-step Quick start
written as flat numbered prose, four separate parameter tables (Required,
Content inputs, Style controls, Advanced), the task lifecycle as a
numbered list, and a Related list mixing alphabetic and recency order.
Restructure for scan-first reading without losing technical content:
- Wrap Quick start in a Steps component (auth -> default model ->
ask the agent).
- Convert all four parameter tables into ParamField definitions grouped
under their existing sub-section headings (Required / Content inputs /
Style controls / Advanced), so types, defaults, and required flags
show as visual chips and long descriptions wrap cleanly.
- Convert the task lifecycle from a numbered list to a 4-row table for
at-a-glance scanning.
- Convert Yes/No checkmarks in both the Supported providers and
Capability matrix tables to ✓ and em-dash, matching the rest of the
media docs.
- Convert the bullet list under Actions into a 3-row table.
- Sentence-case Related entries and alphabetize the Related list.
- Add sidebarTitle so the nav reads 'Video generation' explicitly.
Schema fields, defaults, model refs, env vars, capability declarations,
fallback rules, and provider notes are unchanged. AccordionGroup of 14
provider notes was already alphabetized and is preserved verbatim.
