docs: fold dynamic parameters into a Parameters section - #30912

Dynamic parameters are how every parameter works now (default since v2.25.0), but the docs still split the concept across two sibling sidebar pages, "Parameters" and "Dynamic parameters". That hides form types, conditional parameters, and identity-aware parameters behind a legacy feature name.

This PR folds them into a single Parameters section under Extend templates, with one focused child page per concept. Every code example from both old pages is kept (33 of 33 fenced blocks, including the commented-out daisy-chaining example).

New structure

parameters.md moves to parameters/index.md, so /docs/admin/templates/extending-templates/parameters (and #ephemeral-parameters, which the dashboard links to) keeps working.

Other changes

• docs/redirects.json: /docs/admin/templates/extending-templates/dynamic-parameters redirects to the Parameters section.
• Dashboard docs() links that pointed at dynamic-parameters now point at parameters, or at parameters/compatibility-mode where the link is about compatibility mode (the Storybook assertion is updated to match).
• Inbound doc links updated. Glossary gets a Parameters entry, and Dynamic parameters is kept as the former name.
• Tabs on the old page are replaced with headed sections, per the style guide's rule against tabs for content every reader needs. Each form type and example now has its own anchor.
• Small cleanups in moved prose: sentence-case headings, "Dynamic Parameters" product-name references removed, the stale "Later in 2025..." registry-module sentence and GA announcement copy dropped, "template creation links" corrected to "workspace creation links" for URL autofill.

Not in this PR

Dashboard UI copy still says "Dynamic Parameters" in a few tooltips and helper text (for example, CreateWorkspacePageView.tsx and TemplateParametersPageView.tsx). That's a product copy change and is better handled separately.

Verification

• make gen/docs-manifest, make lint/docs-manifest, make lint/docs-redirects (also with -base origin/main), make lint/emdash, make lint/docs-html: pass
• markdownlint-cli2 and markdown-table-formatter --check on changed docs: pass
• Vale on the new pages: 0 errors, 0 warnings, 0 suggestions
• biome check on the changed site/ files: pass
• A script compared every fenced code block in the old parameters.md and dynamic-parameters.md with the new pages: all 33 are present.
• Relative links and anchors in all changed docs files resolve. The only failures are anchors that were already broken in glossary.md and admin/templates/index.md, which this PR doesn't touch.
• Not done: a rendered preview on the docs site, and running the Storybook interaction test.

This PR was drafted by Superblink (Coder's AI assistant) at the request of @stirby, who will review it and is accountable for it.