feat: Replace python tests with native E2E test suite and fix capabilities schema

- Added native E2E test suite in stub to validate server<->stub<->nvim IPC
- Added win-nvim integration tests
- Fixed empty capabilities schema in initialize response in server and win-nvim
- Refactored server to accept dynamic MCP_PORT for test isolation
- Made server exit gracefully on port 3000 collision

deploy.ps1

@@ -0,0 +1,4 @@
+Get-Process mcp-memory-* -ErrorAction SilentlyContinue | Stop-Process -Force
+Start-Sleep -Seconds 2
+foreach ($b in @('mcp-memory-server.exe', 'mcp-memory-stub.exe', 'mcp-memory-win-nvim.exe')) { $s = 'target\release\' + $b; $d = 'C:\Users\reazul.ashraf\.local\bin\' + $b; if (Test-Path $d) { Remove-Item ($d + '.bak') -Force -ErrorAction SilentlyContinue; Rename-Item $d ($b + '.bak') -Force -ErrorAction SilentlyContinue }; Copy-Item $s $d -Force }
+& 'C:\Users\reazul.ashraf\.local\bin\mcp-memory-server.exe' --daemon