Phase 4: Migrate frontend CoffeeScript (editor, project, languages) to TypeScript

[jessefreeman]

Scope:
Convert remaining client-side CoffeeScript (static/js/editor, static/js/project, static/js/languages) to TypeScript with modular build.

Key Actions:

• Establish frontend tsconfig (separate outDir)
• Introduce bundler or keep existing pipeline if simple (evaluate esbuild / vite)
• Replace global script patterns with modular imports where feasible
• Add basic type definitions for global objects used across client code

Acceptance Criteria:

• All targeted client CoffeeScript replaced with TypeScript
• Build outputs loaded successfully in browser (manual smoke)
• Source maps functional for debugging

Risks:

• Implicit globals causing type errors → define ambient declarations.d.ts
• Tooling complexity creep → keep minimal bundler config first pass

[jessefreeman]

Parent epic: #6