Add unified grammar engine (RVGG, L-systems, ShapeGrammar), robust lexer/parser, SmartEditor and enhanced WebGL renderer

[pghauff73]

Motivation

• Provide a unified, more robust procedural-grammar pipeline for ProGen3d including L-systems, shape grammars and an RVGG (Random Volumetric Geometry Generator) backend to generate richer procedural programs.
• Improve editor UX and reliability by replacing brittle inline parsing/highlighting with a tolerant lexer/parser, better math evaluation, and an interactive SmartEditor with hover tooltips and wrap sync.
• Ship a higher-fidelity WebGL renderer and texture pipeline so generated grammars produce correct UVs, mipmapped textures, Blinn-Phong lighting and an STL export path.

Description

• Added a unified grammar/runtime stack: classes RVGG, ProGen3DGrammar, GrammarLibrary, ShapeGrammar, ProGen3DUnifiedGrammar, GrammarAnalyzer and GrammarVisualizer plus helpers to generate, score and export grammar programs.
• Reworked the editor and parsing code: introduced a robust GrammarLexer, math evaluator (Solution/MathS2_js), variable management, grammar Grammar/Rule/Token classes, Context/Scope execution model and SmartEditor highlighting/diagnostics (tooltip, wrapping, scroll sync, NL/spacing checks).
• Improved WebGL scene subsystem: WebGLSceneRenderer now has textured Blinn-Phong shaders, correct cube UVs, procedural texture generators (solid/checker/noise), batching for opaque/transparent draws, camera/orbit controls and an exportSTL implementation.
• UI and persistence enhancements: randomized grammar generator integration, improved save/load/export flow that persists saved grammars to localStorage (and can download JSON), dropdown chooser population, buttons wired to generation/save/export/open actions, and tutorial/demo loading.

Testing

• No automated tests were added or executed as part of this change.
• The changes include runtime-safe guards and defensive parsing to reduce runtime exceptions during editing and generation, and the new renderer and editor were exercised via manual browser smoke runs during development (no CI tests reported).

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[chatgpt-codex-connector]

Preserve scope precedence in variable substitution

replacevars now sorts variable_list by name length before substitution, which loses the stack-like scoping order for duplicate names. When a rule introduces a shadowed variable (via addVariableInstance), the older outer variable is substituted first and the newer in-scope value is never applied, so expressions like repeat counts/transforms can evaluate with stale values in recursive or nested rule execution. This is a regression from the previous reverse traversal that preferred the most recent binding.

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