Changes:
- Remove manual "Update Visualization" button - Block Layout now auto-updates on input changes like Linear Layout
- Add validation state tracking and button disable on validation errors
- Fix parse error handling - decimals/NaN now show inline errors instead of throwing exceptions
- Adopt LinearLayout's pattern: store NaN for invalid input and validate gracefully
- Add smart validation short-circuiting to prevent confusing cascade errors
- Add disabled button styling for better UX
- Add comprehensive test coverage for new behavior

Technical improvements:
- ParameterForm.getNumberValue() returns NaN instead of throwing
- ParameterForm.onParamsChange() replaces onSubmit for auto-update flow
- ParameterForm.onValidationChange() enables reactive button state
- InputValidator short-circuits derived checks when dependent fields are invalid
- "Show in Linear Layout" button automatically disables when validation fails

Tests:
- Add ParameterForm.test.ts with decimal/NaN input coverage
- Extend InputValidator.test.ts with parse error tests
- Extend BlockLayoutTab.test.ts with validation button behavior tests
- All 168 tests passing

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