Note: re-apply of #92817

### What?

Deprecates the Edge Runtime and the `preferredRegion` route segment
config that only applied to edge runtime with build-time warnings,
TypeScript IDE hints, error documentation pages, and documentation
updates.

### Why?

Edge Runtime in Next.js is being deprecated in favor of the Node.js
runtime (the default). The `preferredRegion` route segment config is
tightly coupled to Edge Runtime and is also being deprecated.

### How?

**Edge Runtime deprecation:**
- Added `warnAboutEdgeRuntime()` helper using `Log.warnOnce` in
`packages/next/src/build/warn-about-edge-runtime.ts`
- Warning fires in `get-page-static-info.ts` (Webpack dev/build +
Turbopack build) and `turbopack-utils.ts` (Turbopack dev) when `runtime
= 'edge'` is detected
- Marked `'edge'` as `@deprecated` in the TypeScript language service
plugin (`rules/config.ts`)
- Created `errors/edge-runtime-deprecated.mdx` with migration guidance
- Updated documentation across 11 files to add deprecation notices or
simplify/remove outdated Edge Runtime references

**`preferredRegion` deprecation:**
- Added `warnAboutPreferredRegion()` helper in the same file
- Warning fires in `get-page-static-info.ts` for both App Router
(`config.preferredRegion`) and Pages Router (`config.config?.regions`)
- Marked `preferredRegion` as `@deprecated` in the TypeScript language
service plugin and the generated types (`next-types-plugin`)
- Created `errors/preferred-region-deprecated.mdx` with migration
guidance (remove the export)
- Updated documentation across 4 files to add deprecation notices

**Tests:**
- Added `test/e2e/edge-runtime-deprecated/` with fixture and assertions
for the edge runtime warning (dev + production)
- Added `test/production/preferred-region-deprecated/` with fixture and
assertions for the preferredRegion warning (production only -- Turbopack
dev does not surface `preferredRegion` from the Rust layer to JS)

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Co-authored-by: Vercel <vercel[bot]@users.noreply.github.com>