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/flip.sexp

@@ -0,0 +1,16 @@
+;; Flip effect - flips image horizontally or vertically
+(require-primitives "geometry")
+
+(define-effect flip
+  :params (
+    (horizontal :type bool :default true)
+    (vertical :type bool :default false)
+  )
+  (let ((result frame))
+    (if horizontal
+        (set! result (geometry:flip-img result "horizontal"))
+        nil)
+    (if vertical
+        (set! result (geometry:flip-img result "vertical"))
+        nil)
+    result))