feat(frameworks): add NestJS support (#220) (#225)

Detect NestJS projects and emit `route` nodes (each linked by a `references`
edge to its handler method) across all four transport layers:

- HTTP controllers: @Controller prefix joined with
  @Get/@Post/@Put/@Patch/@Delete/@Head/@Options/@All
- GraphQL resolvers: @Query/@Mutation/@Subscription
- Microservices: @MessagePattern/@EventPattern
- WebSocket gateways: @SubscribeMessage (prefixed with gateway namespace)

Detected from any @nestjs/* dependency in package.json (falls back to scanning
*.controller.ts/*.resolver.ts/*.gateway.ts). Handles class+method path joining
with empty @Controller()/@Get(), a string-aware balanced-paren arg reader so
GraphQL type thunks (@Query(() => [User])) aren't truncated, stacked decorators
(@UseGuards) when locating the handler, and disambiguates the @Query() GraphQL
method decorator from the REST @Query() param decorator (GraphQL only counts
inside @Resolver classes). Also resolves injected *Service/*Controller refs to
their classes by Nest file-naming convention.

Adds 18 framework tests; updates the README framework table and CHANGELOG.

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