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/strobe.sexp

@@ -0,0 +1,16 @@
+;; Strobe effect - holds frames for choppy look
+(require-primitives "core")
+
+(define-effect strobe
+  :params (
+    (frame_rate :type int :default 12 :range [1 60])
+  )
+  (let* ((held (state-get 'held nil))
+         (held-until (state-get 'held-until 0))
+         (frame-duration (/ 1 frame_rate)))
+    (if (or (core:is-nil held) (>= t held-until))
+        (begin
+          (state-set 'held (copy frame))
+          (state-set 'held-until (+ t frame-duration))
+          frame)
+        held)))