fix: route world NPCs around the west plaza street lamp

Move the western transit point left to clear the lamp with the largest NPC footprint. Document source-based frontend collision verification and allow Jest to run from a clean checkout without the optional local test directory.

jest.config.js

@@ -1,7 +1,11 @@
+const { existsSync } = require('node:fs');
+const { join } = require('node:path');
+
 module.exports = {
   preset: 'ts-jest',
   moduleFileExtensions: ['js', 'json', 'ts'],
-  roots: ['<rootDir>/src', '<rootDir>/test'],
+  // The optional local integration tests are not part of a clean checkout.
+  roots: ['<rootDir>/src', ...(existsSync(join(__dirname, 'test')) ? ['<rootDir>/test'] : [])],
   testRegex: '.*\\.(spec|e2e-spec|integration-spec|perf-spec)\\.ts$',
   transform: {
     '^.+\\.ts$': 'ts-jest',