Add JAX typography, xector primitives, deferred effect chains, and GPU streaming

- Add JAX text rendering with font atlas, styled text placement, and typography primitives
- Add xector (element-wise/reduction) operations library and sexp effects
- Add deferred effect chain fusion for JIT-compiled effect pipelines
- Expand drawing primitives with font management, alignment, shadow, and outline
- Add interpreter support for function-style define and require
- Add GPU persistence mode and hardware decode support to streaming
- Add new sexp effects: cell_pattern, halftone, mosaic, and derived definitions
- Add path registry for asset resolution
- Add integration, primitives, and xector tests

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

sexp_effects/effects/mosaic.sexp

@@ -0,0 +1,30 @@
+;; Mosaic effect - built from primitive xector operations
+;;
+;; Uses:
+;;   pool-frame  - downsample to cell averages
+;;   cell-indices - which cell each pixel belongs to
+;;   gather       - look up cell value for each pixel
+
+(require-primitives "xector")
+
+(define-effect mosaic
+  :params (
+    (cell-size :type int :default 16 :range [4 64] :desc "Size of mosaic cells")
+  )
+  (let* (
+         ;; Pool frame to get average color per cell (returns r,g,b,lum xectors)
+         (pooled (pool-frame frame cell-size))
+         (cell-r (nth pooled 0))
+         (cell-g (nth pooled 1))
+         (cell-b (nth pooled 2))
+
+         ;; For each output pixel, get its cell index
+         (cell-idx (cell-indices frame cell-size))
+
+         ;; Gather: look up cell color for each pixel
+         (out-r (gather cell-r cell-idx))
+         (out-g (gather cell-g cell-idx))
+         (out-b (gather cell-b cell-idx)))
+
+    ;; Reconstruct frame
+    (rgb out-r out-g out-b)))