feat: discoverability + cross-agent slash commands for Ink Theater / Animated Drawing

Makes the doodle-animation capability findable instead of hidden.

Routing (OpenMontage-internal):
- AGENT_GUIDE: Style Playbooks gets an ink-sketch row + a 'hand-drawn doodle'
  routing note (it's a style + engine on the animation / character-animation
  pipelines, NOT a new pipeline).
- animation/idea-director + character-animation/character-design-director point
  to the Ink Theater / Ink Puppet skills for hand-drawn character briefs.

Cross-agent slash commands (/ink-art, /animated-drawing) for Claude Code,
Copilot, Cursor, and Codex — thin pointers to the canonical skills so they stay
in sync. /ink-art = create a vector doodle from scratch (Ink Theater + Ink
Puppet mocap); /animated-drawing = animate a SUPPLIED drawing via Meta
AnimatedDrawings (raster). New skills/creative/animated-drawing.md documents the
Path A setup/run/limits. Codex prompts are user-home only — .codex/prompts/README
explains the copy/symlink step.

  .claude/commands/*.md            (Claude Code)
  .github/prompts/*.prompt.md      (Copilot)
  .cursor/commands/*.md            (Cursor)
  .codex/prompts/*.md + README     (Codex; copy to ~/.codex/prompts)

.github/prompts/animated-drawing.prompt.md

@@ -0,0 +1,9 @@
+---
+description: Animate a SUPPLIED drawing/photo of a character with real mocap (Meta AnimatedDrawings) → raster GIF/MP4. To create a vector doodle from scratch, use /ink-art.
+---
+
+Read `skills/creative/animated-drawing.md`, then set up and run Meta's open-source **AnimatedDrawings** to animate the user's supplied drawing with the requested motion (dance / walk / jump / wave).
+
+- Only for animating an *existing* humanoid drawing/photo. To create a vector doodle from scratch that draws itself → use `/ink-art`.
+- Output is **raster** (the original drawing warped) — no vector, no draw-on reveal.
+- Prefer the turnkey bundled-character path; the auto-rig path needs Docker + ~670 MB models.

.github/prompts/ink-art.prompt.md

@@ -0,0 +1,10 @@
+---
+description: Hand-drawn ink-on-white doodle animation — a character that draws itself then walks/dances/waves, or a deadpan contraption explainer. Vector, deterministic, HyperFrames → MP4.
+---
+
+Read `skills/creative/ink-theater.md` and `ink-theater/README.md`, then build the hand-drawn ink animation the user asks for.
+
+- Use the **Ink Theater** engine (`ink-theater/ink-theater.js`): variable-width ink strokes, seek-safe boil, closed-form spring eases, FABRIK IK, contraption grammar.
+- For a **character that walks / dances / waves / jumps**, use the **Ink Puppet** mocap system: `InkPuppet.create` → `p.drawIn` (self-drawing reveal) → `InkPuppet.choreograph([{clip:'wave_hello'},{clip:'dab'},…])`. **Never hand-tune motion**; add moves via `ink-theater/mocap/bvh2clip.mjs`.
+- Captions = **HTML overlay `<div>`s** (HyperFrames doesn't apply webfonts to SVG `<text>`).
+- Validate (`npx hyperframes lint` + `snapshot`) before rendering.