fix(web): replace next-mdx-remote with marked + raw HTML to avoid CF Workers eval ban

The /docs deploy from #3860 still returned HTTP 500 with
`EvalError: Code generation from strings disallowed for this context`
(captured via `wrangler tail`).

`next-mdx-remote/rsc` compiles MDX to JSX *at runtime* using
`new Function()` style code generation. Cloudflare Workers' security
sandbox bans all dynamic code generation from strings, even from inside
trusted code, so any worker invocation that touched the docs page
threw immediately.

Switch to a build-time markdown -> HTML pipeline:

- Drop `next-mdx-remote` and `gray-matter`. Add `marked` (pure-JS,
  no eval).
- `web/scripts/generate-docs-content.mjs` now runs each markdown
  source through `marked.parse()` (gfm enabled) at build time and
  writes the resulting HTML strings into
  `web/lib/docs-content.generated.ts`.
- `web/app/[locale]/docs/page.tsx` renders each section as
  `<article className="docs-content" dangerouslySetInnerHTML={{ __html: section.html }} />`.
  No MDX runtime, no JSX compilation at request time, just static HTML
  injection.
- `web/app/globals.css` adds a `@layer components` block targeting
  `.docs-content h1..h4, p, a, ul, ol, li, blockquote, code, pre, table,
  thead, th, td, hr, strong`. Same shadcn-themed look that the dropped
  `mdx-components.tsx` provided, applied via CSS instead of React
  component overrides.
- `web/components/docs/mdx-components.tsx` removed.

We lose MDX features (JSX inside markdown), but the docs are pure
markdown anyway. `docs/` remains the SoT; the marketing site renders
identical content with no eval and no fs at runtime.

web/components/docs/mdx-components.tsx

@@ -1,140 +0,0 @@
-import * as React from "react"
-import { cn } from "@/lib/utils"
-
-type WithChildren = { children?: React.ReactNode; className?: string }
-
-export const mdxComponents = {
-  h1: ({ children, className, ...props }: WithChildren) => (
-    <h1
-      className={cn(
-        "mt-8 mb-4 scroll-mt-24 text-4xl font-bold tracking-tight first:mt-0",
-        className,
-      )}
-      {...props}
-    >
-      {children}
-    </h1>
-  ),
-  h2: ({ children, className, ...props }: WithChildren) => (
-    <h2
-      className={cn("mt-12 mb-4 scroll-mt-24 text-2xl font-semibold tracking-tight", className)}
-      {...props}
-    >
-      {children}
-    </h2>
-  ),
-  h3: ({ children, className, ...props }: WithChildren) => (
-    <h3
-      className={cn("mt-8 mb-3 scroll-mt-24 text-xl font-semibold tracking-tight", className)}
-      {...props}
-    >
-      {children}
-    </h3>
-  ),
-  h4: ({ children, className, ...props }: WithChildren) => (
-    <h4
-      className={cn("mt-6 mb-2 scroll-mt-24 text-lg font-semibold tracking-tight", className)}
-      {...props}
-    >
-      {children}
-    </h4>
-  ),
-  p: ({ children, className, ...props }: WithChildren) => (
-    <p className={cn("text-muted-foreground my-4 leading-7", className)} {...props}>
-      {children}
-    </p>
-  ),
-  a: ({ children, href, className, ...props }: WithChildren & { href?: string }) => (
-    <a
-      href={href}
-      className={cn("text-primary font-medium underline underline-offset-4", className)}
-      {...props}
-    >
-      {children}
-    </a>
-  ),
-  ul: ({ children, className, ...props }: WithChildren) => (
-    <ul className={cn("text-muted-foreground my-4 ml-6 list-disc space-y-1", className)} {...props}>
-      {children}
-    </ul>
-  ),
-  ol: ({ children, className, ...props }: WithChildren) => (
-    <ol
-      className={cn("text-muted-foreground my-4 ml-6 list-decimal space-y-1", className)}
-      {...props}
-    >
-      {children}
-    </ol>
-  ),
-  li: ({ children, className, ...props }: WithChildren) => (
-    <li className={cn("leading-7", className)} {...props}>
-      {children}
-    </li>
-  ),
-  blockquote: ({ children, className, ...props }: WithChildren) => (
-    <blockquote
-      className={cn("border-primary/40 my-6 border-l-4 pl-4 italic", className)}
-      {...props}
-    >
-      {children}
-    </blockquote>
-  ),
-  code: ({ children, className, ...props }: WithChildren) => (
-    <code
-      className={cn("bg-muted text-foreground rounded px-1.5 py-0.5 font-mono text-sm", className)}
-      {...props}
-    >
-      {children}
-    </code>
-  ),
-  pre: ({ children, className, ...props }: WithChildren) => (
-    <pre
-      className={cn(
-        "border-border/50 my-4 overflow-x-auto rounded-lg border bg-[#1e1e2e] p-4 font-mono text-sm text-[#cdd6f4] shadow-sm [&_code]:bg-transparent [&_code]:p-0 [&_code]:text-inherit",
-        className,
-      )}
-      {...props}
-    >
-      {children}
-    </pre>
-  ),
-  table: ({ children, className, ...props }: WithChildren) => (
-    <div className="my-6 overflow-x-auto">
-      <table
-        className={cn("border-border w-full border-collapse border text-sm", className)}
-        {...props}
-      >
-        {children}
-      </table>
-    </div>
-  ),
-  thead: ({ children, className, ...props }: WithChildren) => (
-    <thead className={cn("bg-muted", className)} {...props}>
-      {children}
-    </thead>
-  ),
-  th: ({ children, className, ...props }: WithChildren) => (
-    <th
-      className={cn("border-border border px-3 py-2 text-left font-semibold", className)}
-      {...props}
-    >
-      {children}
-    </th>
-  ),
-  td: ({ children, className, ...props }: WithChildren) => (
-    <td
-      className={cn("border-border text-muted-foreground border px-3 py-2", className)}
-      {...props}
-    >
-      {children}
-    </td>
-  ),
-  hr: ({ className, ...props }: { className?: string }) => (
-    <hr className={cn("border-border my-8", className)} {...props} />
-  ),
-  strong: ({ children, className, ...props }: WithChildren) => (
-    <strong className={cn("text-foreground font-semibold", className)} {...props}>
-      {children}
-    </strong>
-  ),
-}