IO-2/SHP-5/PRV-2: PSD import, SVG import + vector/text conversions, persistent disk cache

- effectcraft-psd (L1): PSD/PSB reader from Adobe's published file format spec (layers, groups,
  masks, blend modes, text engine data, lfx2 effects, fill/adjustment layers, vector masks;
  1/8/16/32-bit, RGB/CMYK/Gray/Lab/Indexed, raw/RLE/ZIP) and a minimal writer for fixtures.
- File > Import: importAs footage|composition|compositionLayerSizes, layer (Choose Layer);
  groups -> precomps (pass-through collapses), text -> editable text, styles -> Layer Styles,
  adjustments -> adjustment layers with effects; UI asks the Import Kind for Photoshop files.
- effectcraft-svg (L2): SVG parser (shapes, paths, transforms, use, CSS, gradients) and
  rasteriser; .svg imports as footage, continuously rasterised when the switch is on.
- layer.create: shapesFromVector, shapesFromText, masksFromText, editableText (stub removed).
- Disk cache (render::disk_cache): LZ4 content-keyed frames and layer buffers, LRU size limit
  from prefs, atomic writes, restart persistence; edit.purge clears it, cache.diskStats query;
  viewer frames read/write it and the timeline shows disk-only frames in blue.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

xtask/src/main.rs

@@ -27,10 +27,12 @@ const LAYERS: &[(&str, u8)] = &[
     ("raster", 1),
     ("keyframe", 1),
     ("path", 1),
+    ("psd", 1),
     ("project", 2),
     ("text", 2),
     ("effects", 2),
     ("track", 2),
+    ("svg", 2),
     ("render", 3),
     ("media", 3),
     ("expr", 3),