fix: swagger apis path to src/ + update stale signup/verify test refs

- swagger.ts: changed apis glob from dist/routes/*.js to src/routes/*.ts
  so OpenAPI spec includes demo endpoints during tests (fixes 6 test failures)
- Dockerfile: copy src/ to final stage for runtime swagger-jsdoc
- Updated stale /v1/signup/verify test refs to /v1/signup/free (endpoint
  was removed when free tier was discontinued)

Dockerfile

@@ -53,6 +53,7 @@ RUN npm install --omit=dev
 # Copy compiled artifacts from builder stage
 COPY --from=builder /app/dist ./dist
 COPY --from=builder /app/public ./public
+COPY --from=builder /app/src ./src
 
 # Recreate swagger-ui symlink in production stage
 RUN rm -f public/swagger-ui && ln -s /app/node_modules/swagger-ui-dist public/swagger-ui