improve exclude pattern normalization and directory pruning performance

• Implemented pattern normalization in both the desktop app and Python exporter to seamlessly handle paths that start with the project root folder name.
• Overhauled the Python scanner's directory traversal to use os.walk, enabling early pruning of excluded directories (like node_modules) to drastically improve scan performance.
• Replaced Path.match() with fnmatch in the Python scanner to provide robust, multi-segment glob matching for exclude patterns.
• Added strict validation to the Python exporter's include mode to safely reject raw or absolute patterns that attempt to escape the project root directory.
• Updated the ExcludeRulesEditor UI text to inform users about the new automatic path normalization capabilities.
• Expanded both the TypeScript and Python test suites with comprehensive test cases covering root-prefixed custom patterns, bare directory exclusions, nested exclusions, and normalization edge cases.