pipelines: require meta/animation-runtime-selector in animation-heavy pipelines

Declaratively wire the new Layer 2 animation-runtime dispatcher into the
four pipelines that do meaningful animation authoring:

  - animated-explainer  (generated explainer scenes, kinetic typography)
  - animation           (motion graphics, logo morphs, motion paths)
  - cinematic           (title cards, curved camera moves, prestige easings)
  - screen-demo         (synthetic terminal timing + callout overlays)

Before this, skills/meta/animation-runtime-selector.md was referenced only
in asset-director prose — a fresh-context agent running preflight on the
manifest alone would miss it. Adding it to required_skills: closes the
discovery loop: the reviewer + checkpoint systems now enforce that it
was consulted before authoring animated components.

No schema change required — follows the existing pattern of listing meta
skills (reviewer, checkpoint-protocol, skill-creator) as required.

pipeline_defs/animated-explainer.yaml

@@ -39,6 +39,7 @@ required_skills:
   - meta/reviewer
   - meta/checkpoint-protocol
   - meta/skill-creator
+  - meta/animation-runtime-selector
 
 orchestration:
   mode: executive-producer

pipeline_defs/animation.yaml

@@ -39,6 +39,7 @@ required_skills:
   - pipelines/animation/publish-director
   - meta/reviewer
   - meta/checkpoint-protocol
+  - meta/animation-runtime-selector
 
 orchestration:
   mode: executive-producer

pipeline_defs/cinematic.yaml

@@ -46,6 +46,7 @@ required_skills:
   - pipelines/cinematic/publish-director
   - meta/reviewer
   - meta/checkpoint-protocol
+  - meta/animation-runtime-selector
 
 compatible_playbooks:
   recommended:

pipeline_defs/screen-demo.yaml

@@ -65,6 +65,7 @@ required_skills:
   - pipelines/screen-demo/publish-director
   - meta/reviewer
   - meta/checkpoint-protocol
+  - meta/animation-runtime-selector
 
 compatible_playbooks:
   recommended: