chore: Bump version to v1.3.0

Update version numbers across project for v1.3.0 release:
- CHANGELOG.md: Move [Unreleased] → [1.3.0] - 2025-10-26
- README.md: Update version badge 1.2.0 → 1.3.0
- cli/__init__.py: Update __version__ = "1.3.0"

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

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

cli/__init__.py

@@ -28,7 +28,7 @@ except ImportError:
     open_folder = None
     read_reference_files = None
 
-__version__ = "1.2.0"
+__version__ = "1.3.0"
 
 __all__ = [
     "LlmsTxtDetector",