Windows desktop sessions were failing during early hook execution because the
runtime assumed Git Bash was always installed. That made a missing Git
installation look like a fatal CLI startup regression even though PowerShell is
usually available and sufficient for default hook execution.
This change turns Git Bash lookup into a best-effort probe, leaves SHELL unset
when Git Bash is missing, and falls back to PowerShell for default Windows hook
execution. Explicit bash hooks still fail with a direct installation hint, but
they no longer hard-exit the whole process.
Constraint: Windows users may have PowerShell but no Git for Windows installed
Rejected: Keep hard-exiting on missing Git Bash | makes first-run desktop chat fail for a recoverable missing dependency
Rejected: Bundle Git for Windows into the app | larger distribution and higher maintenance burden than a runtime fallback
Confidence: medium
Scope-risk: moderate
Reversibility: clean
Directive: Treat Git Bash as an optional Windows capability unless a code path explicitly requires bash semantics
Tested: bun test src/server/__tests__/conversation-service.test.ts
Tested: bun -e "await import('./src/utils/windowsPaths.ts'); await import('./src/utils/hooks.ts'); console.log('module-import-ok')"
Not-tested: End-to-end desktop chat startup on a clean Windows Server host without Git installed
Not-tested: Explicit bash hook execution on Windows after the fallback path
Related: GitHub issue #62
