feat(character-animation): add local rigged character pipeline

New beta pipeline for reusable cartoon characters with SVG rigs, pose
libraries, action timelines, and Canvas/Remotion/HyperFrames rendering.

- pipeline_defs/character-animation.yaml: 11-stage manifest
- skills/pipelines/character-animation/: 11 stage director skills
- tools/character/: BaseTool implementations for char design, rigging,
  pose libraries, action timelines, previews, and QA
- schemas/artifacts/{character_design,rig_plan,pose_library,
  action_timeline,character_qa_report}.schema.json: canonical artifacts
- schemas/artifacts/scene_plan.schema.json: extended for character-led
  scenes
- .agents/skills/{canvas-procedural-animation,character-animation-qa,
  character-rigging,pose-library-design,svg-character-animation}/:
  Layer 3 vendor knowledge
- AGENT_GUIDE / PROJECT_CONTEXT / README / ARCHITECTURE / PROVIDERS:
  surface the new pipeline and its capability family
- tools/video/hyperframes_compose.py: SVG character rig support
- tests/contracts/test_character_animation_pipeline.py: contract tests

.agents/skills/character-animation-qa/SKILL.md

@@ -0,0 +1,43 @@
+---
+name: character-animation-qa
+description: Review local character animation with schema checks, Playwright browser previews, frame sampling, and FFmpeg/ffprobe final output checks.
+license: MIT
+---
+
+# Character Animation QA
+
+Use this skill before presenting a character-animation preview or final render.
+
+## Review Layers
+
+1. Schema validation: character design, rig plan, pose library, action timeline.
+2. Static asset checks: referenced parts and backgrounds exist.
+3. Browser preview: load the preview, capture screenshots, collect console errors.
+4. Motion check: compare sampled frames for non-trivial differences.
+5. Final MP4 check: ffprobe metadata, duration, resolution, audio, frame samples.
+6. Agent visual review: inspect sampled frames for detached limbs, bad layers,
+   off-frame characters, unreadable expressions, broken text.
+
+## Playwright Pattern
+
+```ts
+const browser = await chromium.launch();
+const page = await browser.newPage({ viewport: { width: 1280, height: 720 } });
+await page.goto(previewUrl, { waitUntil: "networkidle" });
+await page.screenshot({ path: "preview.png" });
+```
+
+## Pass/Revise/Fail
+
+- `pass`: technical checks pass, acting is readable.
+- `revise`: fixable rig/timeline issue.
+- `fail`: missing assets, blank render, runtime failure, or wrong runtime.
+
+## Sources
+
+- Playwright screenshots:
+  https://playwright.dev/docs/screenshots
+- Playwright page navigation:
+  https://playwright.dev/docs/api/class-page#page-goto
+- FFmpeg/ffprobe should be used for final media probing:
+  https://ffmpeg.org/ffprobe.html