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/trails.sexp

@@ -0,0 +1,20 @@
+;; Trails effect - persistent motion trails
+(require-primitives "image" "blending")
+
+(define-effect trails
+  :params (
+    (persistence :type float :default 0.8 :range [0 0.99])
+  )
+  (let* ((buffer (state-get 'buffer nil))
+         (current frame))
+    (if (= buffer nil)
+        (begin
+          (state-set 'buffer (copy frame))
+          frame)
+        (let* ((faded (blending:blend-images buffer
+                                    (make-image (image:width frame) (image:height frame) (list 0 0 0))
+                                    (- 1 persistence)))
+               (result (blending:blend-mode faded current "lighten")))
+          (begin
+            (state-set 'buffer result)
+            result)))))