Add MATCHA integration module

- Implement MATCHA class with full workflow integration
- Add GeneProgram, PeakTFPrioritizer, and MatchaResult classes
- Integrate with existing peak_gene_corr and motif_scan functionality
- Implement TFstoRankedTFs.rna.only.matcha functionality
- Implement singleprogram.crossdataset.TFprioritize.matcha functionality
- Implement multiprogram.crossdataset.TFprioritize.matcha functionality
- Add example usage and documentation

Co-Authored-By: Claude <noreply@anthropic.com>

Author: xfchen0912

src/scmagnify/external/matcha/__init__.py

@@ -0,0 +1,12 @@
+"""MATCHA: Multi-omic Analysis of TF-CRE-gene Hierarchy for Activity.
+
+This module integrates the MATCHA workflow for mapping gene programs to
+co-accessible peaks and prioritizing transcription factors based on
+chromatin accessibility and gene expression correlations.
+"""
+
+from __future__ import annotations
+
+from ._matcha import MATCHA, GeneProgram, MatchaResult, PeakTFPrioritizer
+
+__all__ = ["MATCHA", "GeneProgram", "MatchaResult", "PeakTFPrioritizer"]