* chore: fix installation directory handling to use .bmad-core as default path
- Remove redundant ./ prefix from default directory
- Update all default paths from ./.bmad-core to .bmad-core
- Add logic to handle direct .bmad-core path selection
- Treat parent as project root when .bmad-core specified
- Simplify directory state detection for existing files
- Remove unknown_existing state type from installer logic
* chore: refactor installer to use modern JS patterns and improve code clarity
## CHANGES
- Replace require with node:path import
- Add block scoping to switch cases
- Remove unused options parameter from update
- Use optional chaining for ideConfig check
- Replace forEach with for...of loops
- Use template literals for string concatenation
- Add early return to avoid else block
- Update spell check dictionary entries
* chore: update dependencies to latest major versions
## CHANGES
- Update @kayvan/markdown-tree-parser to v1.5.0
- Update chalk to v5.4.1 for ESM support
- Update commander to v14.0.0 with Node 20 requirement
- Update fs-extra to v11.3.0
- Update glob to v11.0.3 with new API
- Update inquirer to v12.6.3 with modular design
- Update ora to v8.2.0 with improved features
