feat(dashboard): hand-rolled Rhai parser + symbol table + Vitest

Foundation for upcoming editor features (scope-aware autocomplete,
goto-def / find-usages, source formatter). Hand-rolled recursive
descent in TypeScript with Pratt precedence climbing for expressions,
error-tolerant so partial trees stay usable while the user is typing.
Symbol table walks the AST to produce per-scope declarations, usage
sites, and object-literal field maps. Vitest added as a dev-only
runner; no editor wiring in this commit.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

dashboard/vitest.config.ts

@@ -0,0 +1,15 @@
+// Vitest config for unit-testing the Rhai parser / symbol table /
+// formatter. Kept separate from vite.config.ts because the dev/build
+// pipeline doesn't depend on a test runner.
+//
+// Tests use explicit `import { describe, it, expect } from 'vitest'`
+// to keep globals out of the type environment.
+
+import { defineConfig } from 'vitest/config';
+
+export default defineConfig({
+	test: {
+		include: ['src/lib/rhai/**/*.test.ts'],
+		environment: 'node'
+	}
+});