fix: BMAD install creates .bmad-core/.bmad-core/ directory structure + updates (#223)

* 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

package.json

@@ -23,14 +23,14 @@
     "prepare": "husky"
   },
   "dependencies": {
-    "@kayvan/markdown-tree-parser": "^1.4.2",
-    "chalk": "^4.1.2",
-    "commander": "^9.4.1",
-    "fs-extra": "^11.1.0",
-    "glob": "^8.0.3",
-    "inquirer": "^8.2.5",
+    "@kayvan/markdown-tree-parser": "^1.5.0",
+    "chalk": "^5.4.1",
+    "commander": "^14.0.0",
+    "fs-extra": "^11.3.0",
+    "glob": "^11.0.3",
+    "inquirer": "^12.6.3",
     "js-yaml": "^4.1.0",
-    "ora": "^5.4.1"
+    "ora": "^8.2.0"
   },
   "keywords": [
     "agile",