fix: resolve case-insensitive project switching database lookup issue

Fix project switching bug where case-insensitive matching worked but
caused database lookup failures for subsequent operations.

**Problem:**
- switch_project('personal') succeeded (case-insensitive matching)
- get_current_project() failed with 'Project personal not found'
- Session stored user input case instead of canonical database name

**Solution:**
- Find project by permalink (case-insensitive) in switch_project
- Store canonical project name from database in session
- Use canonical name for all API calls and responses

**Test Coverage:**
- Added comprehensive case-insensitive project switching tests
- Added tests for case preservation in project listings
- Added tests for session state consistency after case switching
- Added error handling tests for non-existent projects

**Files Changed:**
- src/basic_memory/mcp/tools/project_management.py: Fixed switch_project logic
- test-int/mcp/test_project_management_integration.py: Added test coverage

**Test Cases Now Passing:**
- ✅ switch_project('personal') → finds 'Personal' project
- ✅ get_current_project() → works with canonical name
- ✅ Project summary shows stats correctly
- ✅ Case-insensitive matching for all case variations
- ✅ Error handling for non-existent projects

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/basic_memory/services/project_service.py

@@ -668,4 +668,4 @@ class ProjectService:
             database_size=db_size_readable,
             watch_status=watch_status,
             timestamp=datetime.now(),
-        )
+        )