feat(extract): add dynamic import() extraction for JS/TS

[Yalkowni]

What

Adds _dynamic_import_js() — a 65-line helper that detects import() call expressions in JS/TS files and emits imports_from edges from the enclosing function.

Before this change, any module loaded via dynamic import was invisible to the graph. This is a significant blind spot for codebases that use dynamic imports for code splitting, lazy loading, or container isolation (e.g. await import('./mayaEngine.js')).

How

• Detects call_expression nodes whose function child is the import keyword (how tree-sitter-typescript represents import(...))
• Resolves the module path using the same logic as static imports: relative path normalization, .js→.ts/.jsx→.tsx suffix remapping, and tsconfig path aliases
• Emits imports_from edges with confidence: EXTRACTED (deterministic string literals)
• Edge source is the enclosing function, not the file — so the graph reflects where the dynamic load actually happens
• Hooked into walk_calls for JS/TS configs; continues recursing into children so import().then(...) chains still resolve their calls

Supported patterns

const { foo } = await import('./foo.js');       // .js → .ts remapping
import('./queue.js').then(m => m.bar());         // chained .then still resolves
const m = await import(`./template`);           // template literal
await import('@/utils/helpers');                 // tsconfig alias

Tests

• tests/fixtures/dynamic_import.ts — fixture with static import, two dynamic imports in separate functions, one clean sync function
• 5 new tests in tests/test_languages.py:
  • no error on parse
  • all three modules (static + both dynamic) produce imports_from edges
  • dynamic edges carry EXTRACTED confidence
  • edge source is the enclosing function (processInbound), not the file
  • sync function gets no spurious imports_from edges
• All 5 pass alongside the existing 110 tests