Refactor SAV module to follow MultiQC best practices

Apply improvements based on MultiQC module development guidelines:

Critical fixes:
- Add ModuleNoSamplesFound exception when no data found
- Add add_data_source() and add_software_version() calls
- Add write_data_file() call at end of module init
- Export SAVModule class from __init__.py

High priority fixes:
- Change anchor from "SAV" to "sav" (lowercase)
- Add href to Illumina InterOp GitHub repository
- Improve info string (remove leading " - ")

Medium priority improvements:
- Add comprehensive class docstring documenting supported sequencers
- Add scale attributes to all HEADERS entries for semantic coloring
- Add general stats columns (% >= Q30, Yield, % PF, Error Rate)

Low priority improvements:
- Support multiple sequencing runs (removed single-run limitation)
- Add defensive checks with .get() defaults in _clusters_lane_plot()
- Update function type hints to use SAVModule type

Also add multiqc_data* and multiqc_report* to .gitignore.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: ewels

.gitignore

@@ -1,3 +1,6 @@
+multiqc_data*
+multiqc_report*
+
 # Byte-compiled / optimized / DLL files
 __pycache__/
 *.py[cod]

multiqc_sav/modules/sav/__init__.py

@@ -0,0 +1,3 @@
+from .sav import SAVModule
+
+__all__ = ["SAVModule"]