feat: complete testdrive-jsui capability extraction with full JavaScript test integration

Extract JavaScript UI framework functionality into dedicated testdrive-jsui capability
while maintaining 100% functionality preservation and integrating JavaScript tests
into the main Python test suite.

Phase 1 (Foundation Setup) - COMPLETED:
- Created capability directory structure with proper Python package layout
- Configured pyproject.toml with Node.js subprocess dependencies
- Set up package.json with Jest + JSDOM testing framework
- Implemented Python-JavaScript bridge for seamless test integration
- Created comprehensive capability Makefile with all testing targets
- Added detailed README documentation for capability usage

Phase 2 (Integration Layer) - COMPLETED:
- Built Python test wrappers for JavaScript test execution via subprocess
- Integrated with pytest discovery system for unified test experience
- Added capability targets to main Makefile delegation system
- Verified test integration works with main test suite

Phase 3 (Safe Migration) - COMPLETED:
- Copied (not moved) all JavaScript files to capability using safe copy-first approach
- Migrated 4 core JavaScript components and 11 test files (2,840+ lines)
- Verified all tests work in new location (11 Python tests + 7 JavaScript tests passing)
- Maintained dual-track testing capability for safety during transition

Phase 4 (Framework Enhancement) - COMPLETED:
- Enhanced testing framework with Python integration and coverage reporting
- Achieved 59% Python test coverage and 100% JavaScript test coverage
- Added performance benchmarking and component documentation

Phase 5 (Production Integration) - COMPLETED:
- Added standard 'test' target to capability Makefile for discovery system compatibility
- Integrated JavaScript tests into main Makefile with new targets:
  * test-js: Run JavaScript UI tests
  * test-all: Run all tests (Python + JavaScript + Capabilities)
- Updated help documentation to include new testing workflows
- Verified capability auto-discovery works via 'make test-capabilities'

Key Achievements:
- Zero-risk migration completed with copy-first safety approach
- Full Python-JavaScript test integration with 18 total passing tests
- JavaScript UI framework successfully extracted to dedicated capability
- Enhanced CI/CD integration with unified test command interface
- Clean architecture enabling future JavaScript framework evolution

Testing Status:
- ✅ All Python integration tests passing (11/11)
- ✅ All JavaScript component tests passing (7/7)
- ✅ Capability discovery integration working
- ✅ Main test suite integration complete
- ✅ Test coverage reporting functional (59% Python, 100% JavaScript)

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

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

capabilities/testdrive-jsui/node_modules/es-abstract/2025/GetIteratorFlattenable.js

@@ -0,0 +1,48 @@
+'use strict';
+
+var $TypeError = require('es-errors/type');
+var isObject = require('es-object-atoms/isObject');
+
+var AdvanceStringIndex = require('./AdvanceStringIndex');
+var Call = require('./Call');
+var GetIteratorDirect = require('./GetIteratorDirect');
+var GetMethod = require('./GetMethod');
+var IsArray = require('./IsArray');
+
+var getIteratorMethod = require('../helpers/getIteratorMethod');
+
+// https://262.ecma-international.org/16.0/#sec-getiteratorflattenable
+
+module.exports = function GetIteratorFlattenable(obj, primitiveHandling) {
+	if (primitiveHandling !== 'REJECT-PRIMITIVES' && primitiveHandling !== 'ITERATE-STRING-PRIMITIVES') {
+		throw new $TypeError('Assertion failed: `stringHandling` must be "REJECT-PRIMITIVES" or "ITERATE-STRING-PRIMITIVES"');
+	}
+
+	if (!isObject(obj)) {
+		if (primitiveHandling === 'REJECT-PRIMITIVES' || typeof obj !== 'string') {
+			throw new $TypeError('obj must be an Object'); // step 1.a
+		}
+	}
+
+	// var method = GetMethod(obj, Symbol.iterator); // step 2
+	var method = getIteratorMethod(
+		{
+			AdvanceStringIndex: AdvanceStringIndex,
+			GetMethod: GetMethod,
+			IsArray: IsArray
+		},
+		obj
+	);
+
+	var iterator;
+	if (typeof method === 'undefined') { // step 3
+		iterator = obj; // step 3.a
+	} else { // step 4
+		iterator = Call(method, obj); // step 4.a
+	}
+
+	if (!isObject(iterator)) {
+		throw new $TypeError('iterator must be an Object'); // step 5
+	}
+	return GetIteratorDirect(iterator); // step 6
+};