Release 0.4.0

[lrwh]

Summary

• add Codex Desktop-compatible project navigation and project creation
• add per-session model and reasoning selectors with retired-model filtering
• redesign session navigation with compact grouped, collapsible sections
• improve session switching, rendering performance, and working-directory handling
• refresh the desktop layout, responsive message width, and visual palette
• bump the application and package version to 0.4.0

Validation

• python3 -m py_compile $(git ls-files "*.py")
• git diff --check
• built tar.gz and .deb artifacts
• verified Debian package metadata reports version 0.4.0
• packaged application remained running in offscreen mode for 15 seconds

Notes

PyInstaller reports the existing optional libtiff.so.5 image-format plugin warning. PNG/JPEG UI assets and application startup are unaffected.