fix: syncDirectory — guard same-path copy and skip nested .git dirs

Two bugs causing 'EACCES: permission denied, copyfile' when source
and target are the same path (e.g. wizard with sourceDir == mosaicHome):

1. No same-path guard — syncDirectory tried to copy every file onto
   itself; git pack files are read-only (0444) so copyFileSync fails.
2. excludeGit only matched top-level .git — nested .git dirs like
   sources/agent-skills/.git were copied, hitting the same permission
   issue.

Fixes:
- Early return when resolve(source) === resolve(target)
- Match .git dirs at any depth via dirName and relPath checks
- Skip files inside .git/ paths

Added file-ops.test.ts with 4 tests covering all cases.

packages/mosaic/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@mosaic/mosaic",
-  "version": "0.0.3",
+  "version": "0.0.3-1",
   "description": "Mosaic agent framework — installation wizard and meta package",
   "type": "module",
   "main": "dist/index.js",