Replace batch DAG system with streaming architecture

- Remove legacy_tasks.py, hybrid_state.py, render.py
- Remove old task modules (analyze, execute, execute_sexp, orchestrate)
- Add streaming interpreter from test repo
- Add sexp_effects with primitives and video effects
- Add streaming Celery task with CID-based asset resolution
- Support both CID and friendly name references for assets
- Add .dockerignore to prevent local clones from conflicting

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

sexp_effects/effects/emboss.sexp

@@ -0,0 +1,13 @@
+;; Emboss effect - creates raised/3D appearance
+(require-primitives "blending")
+
+(define-effect emboss
+  :params (
+    (strength :type int :default 1 :range [0.5 3])
+    (blend :type float :default 0.3 :range [0 1])
+  )
+  (let* ((kernel (list (list (- strength) (- strength) 0)
+                       (list (- strength) 1 strength)
+                       (list 0 strength strength)))
+         (embossed (convolve frame kernel)))
+    (blending:blend-images embossed frame blend)))