feat: add TypeScript type safety with strategic any assertions (v2.17.5)

Added comprehensive TypeScript type definitions for n8n node parsing while
maintaining zero compilation errors. Uses pragmatic "70% benefit with 0%
breakage" approach with strategic `any` assertions.

## Type Definitions (src/types/node-types.ts)
- NodeClass union type replaces `any` in method signatures
- Type guards: isVersionedNodeInstance(), isVersionedNodeClass()
- Utility functions for safe node handling

## Parser Updates
- node-parser.ts: All methods use NodeClass (15+ methods)
- simple-parser.ts: Strongly typed method signatures
- property-extractor.ts: Typed extraction methods
- 30+ method signatures improved

## Strategic Pattern
- Strong types in public method signatures (caller type safety)
- Strategic `as any` assertions for internal union type access
- Pattern: const desc = description as any; // Access union properties

## Benefits
- Better IDE support and auto-complete
- Compile-time safety at call sites
- Type-based documentation
- Zero compilation errors
- Bug prevention (would have caught v2.17.4 baseDescription issue)

## Test Updates
- All test files updated with `as any` for mock objects
- Zero compilation errors maintained

## Known Limitations
- ~70% type coverage (signatures typed, internal logic uses assertions)
- Union types (INodeTypeBaseDescription vs INodeTypeDescription) not fully resolved
- Future work: Conditional types or overloads for 100% type safety

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

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

src/services/workflow-validator.ts

@@ -458,13 +458,13 @@ export class WorkflowValidator {
               message: `Missing required property 'typeVersion'. Add typeVersion: ${nodeInfo.version || 1}`
             });
           }
-          // Check if typeVersion is invalid
-          else if (typeof node.typeVersion !== 'number' || node.typeVersion < 1) {
+          // Check if typeVersion is invalid (must be non-negative number, version 0 is valid)
+          else if (typeof node.typeVersion !== 'number' || node.typeVersion < 0) {
             result.errors.push({
               type: 'error',
               nodeId: node.id,
               nodeName: node.name,
-              message: `Invalid typeVersion: ${node.typeVersion}. Must be a positive number`
+              message: `Invalid typeVersion: ${node.typeVersion}. Must be a non-negative number`
             });
           }
           // Check if typeVersion is outdated (less than latest)