Consolidate duplicated infrastructure content in dapp-share.mdx

[bgravenorst]

Problem

embedded-wallets/sdk/ios/advanced/dapp-share.mdx duplicates content from the Embedded Wallets infrastructure page across two sections:

• "Embedded Wallets infrastructure at a glance" (lines 7-28) reproduces the share-splitting explanation (ShareA, ShareB, ShareC, 2-of-3 reconstruction) that already lives on the infrastructure page.
• "Dapp share in iOS" (lines 49-53) repeats the dapp share definition nearly verbatim from the end of the "Mobile platform user experience" section (lines 45-47).

The "Mobile platform user experience" section (lines 30-47) is also largely background explanation that could be condensed.

Suggested fix

1. Replace the "Embedded Wallets infrastructure at a glance" section with a 1-2 sentence summary and a link to the infrastructure page.
2. Condense "Mobile platform user experience" to 2-3 sentences covering the key point: on mobile, browser storage is unreliable because users may unknowingly clear it, so a dapp share provides a backup.
3. Remove the duplicated definition in "Dapp share in iOS" (lines 51-53) since it repeats lines 45-47.

Files affected

• embedded-wallets/sdk/ios/advanced/dapp-share.mdx