[QDP] Add PyTorch shape validation

[guan404ming]

Purpose of PR

• Add shape validation for PyTorch tensors (1D for single sample, 2D for batch encoding)
• Support batch encoding for 2D PyTorch tensors via encode_batch()
• Restore accidentally removed performance comments from [QDP] Simplify Python API with unified encode() method #803

Related Issues or PRs

• Related to [QDP] QDP POC Roadmap #799

Changes Made

• Bug fix
• New feature
• Refactoring
• Documentation
• Test
• CI/CD pipeline
• Other

Breaking Changes

• Yes
• No

Checklist

• Added or updated unit tests for all changes
• Added or updated documentation for all changes
• Successfully built and ran all unit tests or manual tests locally
• PR title follows "MAHOUT-XXX: Brief Description" format (if related to an issue)
• Code follows ASF guidelines

[guan404ming]

cc @ryankert01 @400Ping

[viiccwen]

Looks great!
I found current fn encode contains repeated 1D / 2D shape-matching logic across NumPy and PyTorch paths, which makes the function grow to ~150+ lines and slightly harder to scan at a glance.

Maybe it might be worth refactoring it into small helper functions in a follow-up PR?

I don’t think this needs to block the current change, just leaving this as a note for potential future cleanup : )

[guan404ming]

Just go ahead for it thanks!