test: implement comprehensive testing improvements from PR #104 review

Major improvements based on comprehensive test suite review:

Test Fixes:
- Fix all 78 failing tests across logger, MSW, and validator tests
- Fix console spy management in logger tests with proper DEBUG env handling
- Fix MSW test environment restoration in session-management.test.ts
- Fix workflow validator tests by adding proper node connections
- Fix mock setup issues in edge case tests

Test Organization:
- Split large config-validator.test.ts (1,075 lines) into 4 focused files
- Rename 63+ tests to follow "should X when Y" naming convention
- Add comprehensive edge case test files for all major validators
- Create tests/README.md with testing guidelines and best practices

New Features:
- Add ConfigValidator.validateBatch() method for bulk validation
- Add edge case coverage for null/undefined, boundaries, invalid data
- Add CI-aware performance test timeouts
- Add JSDoc comments to test utilities and factories
- Add workflow duplicate node name validation tests

Results:
- All tests passing: 1,356 passed, 19 skipped
- Test coverage: 85.34% statements, 85.3% branches
- From 78 failures to 0 failures

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

tests/factories/node-factory.ts

@@ -2,6 +2,31 @@ import { Factory } from 'fishery';
 import { faker } from '@faker-js/faker';
 import { ParsedNode } from '../../src/parsers/node-parser';
 
+/**
+ * Factory for generating ParsedNode test data using Fishery.
+ * Creates realistic node configurations with random but valid data.
+ * 
+ * @example
+ * ```typescript
+ * // Create a single node with defaults
+ * const node = NodeFactory.build();
+ * 
+ * // Create a node with specific properties
+ * const slackNode = NodeFactory.build({
+ *   nodeType: 'nodes-base.slack',
+ *   displayName: 'Slack',
+ *   isAITool: true
+ * });
+ * 
+ * // Create multiple nodes
+ * const nodes = NodeFactory.buildList(5);
+ * 
+ * // Create with custom sequence
+ * const sequencedNodes = NodeFactory.buildList(3, {
+ *   displayName: (i) => `Node ${i}`
+ * });
+ * ```
+ */
 export const NodeFactory = Factory.define<ParsedNode>(() => ({
   nodeType: faker.helpers.arrayElement(['nodes-base.', 'nodes-langchain.']) + faker.word.noun(),
   displayName: faker.helpers.arrayElement(['HTTP', 'Slack', 'Google', 'AWS']) + ' ' + faker.word.noun(),