[v2] Extract WebGL into @satus/webgl

[arzafran]

Moved from darkroomengineering#97

Problem

27 files + 5 production dependencies (~17% of the codebase) for a feature most projects won't use. Even though it's lazy-loaded, it's still:

• In node_modules (inflating install time with Three.js + R3F + postprocessing)
• In the mental model (developers see webgl/, GlobalCanvas, FlowMap, Fluid, PostProcessing)
• Leaking dev tools into production (Theatre.js imported unconditionally in fluid/flowmap components)

Proposal

Extract lib/webgl/ into @satus/webgl package. The OptionalFeatures / Wrapper component already handles lazy loading — just needs a package boundary.

Also Fix: Theatre.js Production Leak

Theatre.js imports in fluid/index.tsx and flowmaps/index.tsx need to be gated behind process.env.NODE_ENV === 'development' or extracted into a dev-only hook.

Tasks

• Fix Theatre.js unconditional imports (can be done independently)
• Extract lib/webgl/ into @satus/webgl package
• Extract components/effects/animated-gradient/ (depends on WebGL)
• Update Wrapper component to optionally support webgl prop
• Remove 5 production dependencies from base package.json
• Document @satus/webgl setup and usage

[feledori]

Keeping open as future consideration. This is an advanced starter so WebGL stays in for now. Extraction to @satus/webgl makes sense long-term but not urgent.