Update frontmatter descriptions across Embedded Wallets content

[bgravenorst]

Problem

Over 120 files in embedded-wallets/ have description frontmatter that doesn't meet editorial
standards (see .cursor/rules/markdown-formatting.mdc):

1. Uses "Web3Auth" instead of "Embedded Wallets" in the description field. Per
   product-embedded-wallets.mdc, the product name in prose and metadata should be
   "Embedded Wallets" (not "Web3Auth").

2. Pipe-delimited keyword strings instead of SEO sentences. Most descriptions follow the
   pattern 'Web3Auth <Platform> SDK - <Feature> | Embedded Wallets'. The style guide requires
   a single descriptive sentence for SEO and previews.

3. Redundant sidebar_label on some pages where the value duplicates what the title already
   provides.

Example (current)

description: 'Web3Auth iOS SDK - Using Custom Authentication | Embedded Wallets'

Example (expected)

description: Authenticate users with your own identity provider using the Embedded Wallets iOS SDK.

Scope

All .mdx files under embedded-wallets/ with a description field referencing "Web3Auth."
This includes:

• sdk/ (iOS, Android, React, React Native, Vue, JS, Flutter, Unity, Unreal, Node) — ~100 files
• dashboard/ — ~8 files
• infrastructure/ — 3 files
• connect-blockchain/ — 1 file

Suggested approach

1. Rewrite each description as a single sentence that uses "Embedded Wallets" as the product
   name, describes what the page covers, and works as an SEO snippet.
2. Remove sidebar_label where it duplicates the title.
3. Validate that no page has both a title frontmatter field and a duplicate # Heading.

[lannathompson65-arch]

"Looks good-- the fronted update appears cleaner and consistent with the current issue scope."