Incorporate art-dag-mono repo into artdag/ subfolder

Merges full history from art-dag/mono.git into the monorepo
under the artdag/ directory. Contains: core (DAG engine),
l1 (Celery rendering server), l2 (ActivityPub registry),
common (shared templates/middleware), client (CLI), test (e2e).

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

git-subtree-dir: artdag
git-subtree-mainline: 1a179de547
git-subtree-split: 4c2e716558

artdag/test/sexp_effects/effects/datamosh.sexp

@@ -0,0 +1,14 @@
+;; Datamosh effect - glitch block corruption
+
+(define-effect datamosh
+  :params (
+    (block_size :type int :default 32 :range [8 128])
+    (corruption :type float :default 0.3 :range [0 1])
+    (max_offset :type int :default 50 :range [0 200])
+    (color_corrupt :type bool :default true)
+  )
+  ;; Get previous frame from state, or use current frame if none
+  (let ((prev (state-get "prev_frame" frame)))
+    (begin
+      (state-set "prev_frame" (copy frame))
+      (datamosh frame prev block_size corruption max_offset color_corrupt))))