fix(windows): port shared desktopdev compatibility fixes

[Kaguya-19]

Summary

• port shared Windows compatibility fixes from desktopdev without Electron desktop shell/package/release changes
• improve Windows bash runner lifecycle, output decoding, and read-only permission classification
• add cross-platform spawn/path/config/session fixes plus clearer web_search setup messaging

Tests

• git diff --check
• node --import tsx --test tests/tool/builtin/bash/commandRunner.test.ts tests/tool/builtin/bash/permissions.test.ts
• pnpm --dir ui exec vitest run server/utils/pilotPaths.test.js server/utils/processSpawn.test.js src/components/chat/view/subcomponents/MessageComponent.tool-error.test.tsx
• npm run build

Notes

• UI full typecheck was checked separately and still hits broad existing React/lucide/settings type conflicts not introduced by this branch.