feat: add hierarchical tag support with exclusion patterns

[callumalpass]

Summary

Implements hierarchical tag support for Obsidian nested tags as requested in issue #584.

Features

• Hierarchical matching: Searching for t/ef now matches child tags like t/ef/project, t/ef/task, t/ef/bug
• Exclusion patterns: Support for -t/ef/bug to exclude specific tags and their children
• Backward compatibility: Existing substring matching preserved (e.g., proj still matches project/alpha)

Implementation

• Enhanced FilterUtils with matchesHierarchicalTag() and matchesTagConditions() methods
• Updated FilterBar tag filtering to use hierarchical matching for "contains" operations
• Enhanced project autosuggester required tags filtering
• Improved task identification by tags with hierarchical support

Test Coverage

• All existing tests pass
• TypeScript compilation succeeds
• Manual testing confirms all features work correctly
• No performance regressions

Examples

# Now supported in FilterBar and Project Autosuggester:
- "t/ef"              # Matches: t/ef, t/ef/project, t/ef/task, t/ef/bug
- "-t/ef/bug"         # Excludes: t/ef/bug, t/ef/bug/critical  
- "proj"              # Still matches: project/alpha (backward compatibility)
- ["t/ef", "-t/ef/bug"]  # Include t/ef hierarchy, exclude t/ef/bug branch

Fixes #584