gegl: enhancer presets + export, LSAN suppressions (wt0)

M9 (task wt0): GEGL quick-enhance (optional, feature-gated).

- src/enhancer.{c,h}: 8 built-in presets (Auto-fix, Brightness, Contrast,
  Saturation, Warm, Cool, Sharpen, Denoise) using gegl:stretch-contrast,
  gegl:exposure, gegl:brightness-contrast, gegl:saturation, gegl:color-enhance,
  gegl:unsharp-mask, gegl:noise-reduction. enhancer_apply via buffer-source +
  buffer-sink pipeline; enhancer_export via gegl:jpg-save. User graph presets
  deferred (NOT_SUPPORTED in v1).
- meson: gegl_dep conditional (-DHAVE_GEGL); enhancer.c in libggae.
- tests: unit test_enhancer (presets dims+non-zero, export file written).
  LSAN suppressions for GEGL third-party init/node leaks.
- 20/20 green, ASan clean (with GEGL lib suppressions).

0 files changed, 0 insertions, 0 deletions