docs: add Builder Code attribution troubleshooting

[sanjeebdas1979]

What changed? Why?

Notes to reviewers

How has it been tested?
What changed? Why?

Added a troubleshooting section to the Builder Codes for App Developers documentation.

The new section helps developers diagnose cases where an onchain transaction succeeds but does not appear in Builder Code analytics. It explains how to verify the ERC-8021 attribution suffix in transaction calldata and clarifies that a transaction without the suffix cannot be attributed to the developer's Builder Code.

This should make Builder Code integration issues easier to debug, especially when developers are testing transactions outside the Base App.

Notes to reviewers

This is a documentation-only change. No application or protocol code is modified.

How has it been tested?

Reviewed the MDX formatting and verified that the new section follows the existing Builder Codes documentation structure and terminology.

[cb-heimdall]

🟡 Heimdall Review Status

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