[BUG] Codebase indexing silently skips .txt files #931

Describe the bug
The indexer processes .md files correctly, but .txt files in the same folders are silently skipped

To Reproduce

1. Workspace folder containing README.md and manual.txt
2. Enable Codebase Indexing; wait for green status
3. Semantic search for content that exists only in the .txt file → not found
4. Confirm in Qdrant: scroll filtered on filePath containing .txt returns zero points; .md returns the expected points

Expected behavior
.txt files get indexed (they don't need tree-sitter — plain line-based chunking would suffice)
This is what the documentation states: https://docs.zoocode.dev/features/codebase-indexing#file-filtering

What version of zoo are you running
3.68.0