docs: add swidge protocol interface

[ihsraham]

Summary

• Adds a new Swidge Protocol Interface SDK page for the shared route interface introduced in tetherto/wdk-wallet#39.
• Defines swidge as supporting swap-only, bridge-only, and combined swap and bridge routes through one quote, execute, and status interface.
• Links swidge from the SDK navigation, module index, getting started page, and protocol integration docs.
• Adds guidance that standalone swap and bridge interfaces remain supported today and are expected to be deprecated in a future release after swidge provider coverage is available.
• Updates the public WDK skill references with the swidge quote, execute, and status flow, including the human confirmation requirement for execution.
• Adds a changelog entry for the new Swidge Protocol Interface docs page.
• Expands the README with Fumadocs setup, local preview, smoke-test routes, and validation commands.
• Fixes /llms-full.txt local preview and copy behavior by serving the tracked static artifact, removing the conflicting dynamic route, pinning matching React versions, and preventing failed fetch responses from being copied as docs content.

Validation

• git diff --check
• npm run check:meta
• LINK_CHECK_EXTERNAL=false npm run check:links
• npm run build
• curl http://localhost:3001/llms-full.txt returns 200 text/plain and includes the swidge section.

Notes

• Documents the current interface surface from tetherto/wdk-wallet#39: quoteSwidge, executeSwidge, and getSwidgeStatus.
• Does not document getSupportedAssets or getSupportedChains as available because they are not present in the linked implementation yet.
• No package release entry is included because this documents an interface in review, not a released package version.
• The LLM copy fix avoids the Next conflict where both public/llms-full.txt and src/app/llms-full.txt/route.ts handled the same path, which could cause the copy action to copy a 500 response body.

[lokeshagrawal99]

Just want to clarify the use case of Swidge interface, its not just for providers who combine swap + bridge txn in one txn. At some places I see the definition written as its only for swap + bridge txn, but thats not true and it should be corrected.

It can be used by 3 types of providers/txns:

1. Just swap providers/txns
2. Just bridge providers/txns
3. Swap + bridge providers/txns

Swidge also supports any type of route between different tokens and different chains.

[ihsraham]

addressed in 67bf7d8. updated the swidge wording across the docs, changelog, and skill references so it covers swap-only, bridge-only, and combined swap and bridge routes. also added local preview and validation instructions to the README.