Fix hatchling direct reference error for BaSiCPy (#15)

* Add flatfield optional dependency with QI2lab/BaSiCPy

- Add [flatfield] optional dependency group
- Install basicpy from QI2lab/BaSiCPy GitHub repo
- Include matplotlib for flatfield visualization
- Update [all] to include flatfield

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

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

* Fix hatchling direct reference error for BaSiCPy

Allow direct Git references in optional dependencies by setting
tool.hatch.metadata.allow-direct-references = true

Fixes CI failure in PR #14

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

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

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: hongquanli

pyproject.toml

@@ -80,6 +80,9 @@ Documentation = "https://github.com/cephla/tilefusion#readme"
 Repository = "https://github.com/cephla/tilefusion"
 Issues = "https://github.com/cephla/tilefusion/issues"
 
+[tool.hatch.metadata]
+allow-direct-references = true
+
 [tool.hatch.build.targets.wheel]
 packages = ["src/tilefusion", "gui", "scripts"]