docs: replace fd:// examples with S3 home directory paths

[amanbagrecha]

Summary

• replace fd:// references in live docs with explicit S3 home directory examples using s3://fused-users/basic-tier/<handle>/...

Notes

• this change updates active docs under docs/
• archived references under docs_backup_jan2026/ and the non-doc code reference in src/app-iframe/python/gabe.py were left unchanged

[CLAassistant]

All committers have signed the CLA.

[MaxLenormand]

Not sure why this one isn't passing
You might need to close & re-open a PR @amanbagrecha
We've seen this before

[MaxLenormand]

Use your own path: s3://fused-user/fused/aman/ and tell people to change with theirs directly