Cleanup nft logic from codebase

[andreygLime]

Detailed description:

This PR removes all NFT-related logic from the codebase. The cleanup includes:

• Removal of NFT handlers (transfer and fee-message handlers)
• Removal of NFT-related read-only handlers
• Removal of NFT clients
• Cleanup of NFT references across services, watchers, and helpers
• Updated documentation to reflect the removal of NFT functionality

The codebase now focuses exclusively on fungible token transfers, simplifying the architecture and reducing maintenance overhead.

Special notes for your reviewer:

This is a cleanup PR that removes NFT functionality. All NFT-related code, handlers, and tests have been removed. The changes exclude unit and e2e test files as those will be updated separately.

Checklist

• Documentation added
• Tests updated

[codecov]

Codecov Report

❌ Patch coverage is 89.47368% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 64.48%. Comparing base (1d0e38f) to head (5875bfe).

Files with missing lines	Patch %	Lines
app/process/watcher/transfer/watcher.go	33.33%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##               v2     #927      +/-   ##
==========================================
+ Coverage   64.36%   64.48%   +0.12%     
==========================================
  Files          86       82       -4     
  Lines        6763     5736    -1027     
==========================================
- Hits         4353     3699     -654     
+ Misses       2194     1852     -342     
+ Partials      216      185      -31     

Flag	Coverage Δ
unittests	64.48% <89.47%> (+0.12%)	⬆️

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