chore: optimize operator naming

[Jay-ju]

In the current progress, if the scan is of the Python version, its display is not user-friendly.
Therefore, this PR attempts to fix this issue.
The main approach is to convert PythonFunction into a specific Datasource Scan, for example
Before PR

tests/io/lancedb/test_lancedb_reads.py 🗡️ 🐟[1/1] ⠁    PythonFunction Scan | [00:00:00] 
🗡️ 🐟[1/1] ⠁    PythonFunction Scan | [00:00:00] 2 rows out, 0 B bytes read
🗡️ 🐟[1/1] ✓    PythonFunction Scan | [00:00:00] 2 rows out, 0 B bytes read  

After PR

tests/io/lancedb/test_lancedb_reads.py 🗡️ 🐟[1/1] ⠁             Lance(Python) Scan | [00:00:00] 
🗡️ 🐟[1/1] ⠁             Lance(Python) Scan | [00:00:00] 2 rows out, 0 B bytes read 
🗡️ 🐟[1/1] ✓             Lance(Python) Scan | [00:00:00] 2 rows out, 0 B bytes read        

Changes Made

Related Issues

Checklist

• Documented in API Docs (if applicable)
• Documented in User Guide (if applicable)
• If adding a new documentation page, doc is added to docs/mkdocs.yml navigation
• Documentation builds and is formatted properly (tag @/ccmao1130 for docs review)

[greptile-apps]

Greptile Summary

This PR enhances operator naming for Python-based scan operations by replacing generic "PythonFunction Scan" names with more descriptive source-specific names like "Lance(Python) Scan", "DuckDB(Python) Scan", "ClickHouse(Python) Scan", etc.

The changes restructure the FileFormatConfig::PythonFunction enum variant from a simple unit variant to a struct variant containing three optional fields: source_type, module_name, and function_name. This metadata enables intelligent source type inference through pattern matching on module names in the new infer_source_type_from_module() method.

Key modifications include:

1. Enhanced FileFormatConfig Structure: The PythonFunction variant now captures contextual metadata about the underlying data source, allowing the system to distinguish between different Python-based sources.

2. Intelligent Display Name Generation: The var_name() method in file_format_config.rs now returns a String instead of &'static str and includes logic to infer source types from module names (e.g., "daft.io.lance" → "Lance(Python)").

3. Progress Bar Optimization: The progress bar display logic in progress_bar.rs implements smart truncation that prioritizes preserving data source type information for Scan operations, with the maximum pipeline name length increased from 22 to 30 characters.

4. Consistent Pattern Matching Updates: All files that pattern match on FileFormatConfig::PythonFunction have been updated to handle the new struct variant, maintaining backward compatibility through wildcard destructuring.

The implementation integrates with Daft's existing DataSource shim pattern, where Python data sources are bridged to the Rust scan operator system. This improves debugging and monitoring by making operator types clearly distinguishable in query plans, logs, and progress displays.

Confidence score: 4/5

• This PR is safe to merge with minimal risk of breaking existing functionality
• Score reflects well-structured changes with proper backward compatibility handling, though the hardcoded string matching in source type inference could be brittle
• Pay close attention to src/common/file-formats/src/file_format_config.rs for the source type inference logic

_{10 files reviewed, no comments}

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[codecov]

Codecov Report

❌ Patch coverage is 70.37037% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.29%. Comparing base (f227eac) to head (1ca03ee).

Files with missing lines	Patch %	Lines
src/common/file-formats/src/file_format_config.rs	64.28%	5 Missing ⚠️
src/common/file-formats/src/lib.rs	0.00%	1 Missing ⚠️
src/common/file-formats/src/python.rs	0.00%	1 Missing ⚠️
src/daft-scan/src/lib.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5204      +/-   ##
==========================================
- Coverage   74.82%   74.29%   -0.54%     
==========================================
  Files         974      974              
  Lines      123656   124372     +716     
==========================================
- Hits        92529    92402     -127     
- Misses      31127    31970     +843     

Files with missing lines	Coverage Δ
daft/io/__shim.py	94.11% <100.00%> (ø)
daft/io/_generator.py	97.36% <ø> (ø)
daft/io/lance/lance_scan.py	90.83% <ø> (-3.06%)	⬇️
src/daft-local-execution/src/sources/scan_task.rs	76.94% <ø> (ø)
src/daft-micropartition/src/micropartition.rs	83.48% <ø> (-0.94%)	⬇️
src/daft-scan/src/glob.rs	89.42% <ø> (ø)
src/daft-scan/src/python.rs	64.60% <100.00%> (+0.47%)	⬆️
src/common/file-formats/src/lib.rs	77.77% <0.00%> (ø)
src/common/file-formats/src/python.rs	36.50% <0.00%> (ø)
src/daft-scan/src/lib.rs	67.00% <0.00%> (ø)
... and 1 more

... and 28 files with indirect coverage changes

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[universalmind303]

@srilman This seems pretty relevant to the changes you've made with observability & logging for udf's. Could you take a look at this one?

[srilman]

@Jay-ju I feel like there should be a nicer way to do this using the def name or def display_name in DataSourceShim or ScanOperator instead of this matching method.

[srilman]

I'd prefer not to have all this specialization here if possible, is this necessary? Can we just name them Read {} or Scan {} instead

[Jay-ju]

@Jay-ju I feel like there should be a nicer way to do this using the def name or def display_name in DataSourceShim or ScanOperator instead of this matching method.

@srilman The operator name is now displayed as you suggested. However, there's one remaining issue: the progress bar in on-ray mode still can't be controlled. This needs to be looked into as a to-do item. But currently, the progress bar in on-ray mode is also missing very little content.