Implement PowerShell language server integration using PowerShell Editor
Services (PSES). The implementation includes:
- PowerShellLanguageServer class with automatic PSES download and setup
- Support for PowerShell file extensions: .ps1, .psm1, .psd1
- Symbol detection using PSES format: "function FuncName ()"
- 7 basic tests + 2 integration tests covering:
- Document symbols and function detection
- Within-file references
- Cross-file go-to-definition
- SerenaAgent find_symbol and find_references
Requires: pwsh (PowerShell 7+) in PATH. PSES auto-downloads on first use.
