v0.6.0

Release 0.6.0

- SVG-aware export sizing in Save As: width/height/scale controls
  computed from the source SVG's intrinsic size, re-rendering from
  the document rather than resampling the preview. Also adds JPEG
  quality and PNG compression controls, persisted as defaults.
- Always-on-top window pin toggle (P shortcut, right-click menu),
  session-only and never persisted.
- Pin to discrete GPU on hybrid-graphics systems, and cache the gamma
  shader's uniform locations at link time instead of querying them on
  every paint call.
- Add the MIT LICENSE and full third-party attribution notices
  (THIRD-PARTY-LICENSES.md), surfaced in-app via the right-click menu;
  calls out rawloader's LGPL-2.1 license explicitly.