feat: implement plugin infrastructure for rendering engines

Added comprehensive plugin system for independent JavaScript UI development:

**Plugin Infrastructure:**
- Extended existing MarkiTect plugin system with RenderingEnginePlugin base class
- Added RENDERING plugin type to PluginType enum
- Created RenderingConfig for asset management and deployment
- Implemented RenderingEngineManager for plugin discovery and lifecycle

**TestDrive JSUI Plugin:**
- Extracted JavaScript UI components to independent testdrive-jsui plugin
- Created standalone development environment (no Python required)
- Implemented compass-positioned control panels (NW, NE, E, SE)
- Added clean JSON configuration interface for Python↔JavaScript data transfer

**Asset Management:**
- Development mode: serve assets directly from plugin source directory
- Production mode: deploy to _markitect/plugins/[plugin-name]/ structure
- Configurable asset URLs and deployment strategies
- Support for external dependencies (CDN resources)

**Standalone Development:**
- testdrive-jsui/test.html for browser-based development
- Package.json with npm scripts for development server
- Complete separation of JavaScript development from Python environment
- Hot reload and standard web development workflow

**Integration Demo:**
- demo_plugin_integration.py showcasing all plugin capabilities
- Standalone, plugin discovery, production deployment examples
- Asset URL generation for different deployment modes

This enables JavaScript-first development while maintaining clean integration
with the MarkiTect Python ecosystem. Developers can now work on UI components
independently using standard web development tools and workflows.

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

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

testdrive-jsui/static/js/controls/edit-control.js

@@ -0,0 +1,70 @@
+/**
+ * Edit Control - Document editing tools and actions
+ * Implements the Robustness Principle with Fail Fast mode support
+ */
+
+class EditControl {
+    constructor() {
+        this.control = Object.create(Control);
+        this.control.config = {
+            icon: '✏️',
+            title: 'Edit',
+            className: 'edit-control',
+            defaultContent: 'Document editing tools',
+            ariaLabel: 'Edit Control',
+            position: 'e'
+        };
+
+        // Bind methods to control
+        this.control.buildContent = () => {
+            const content = this.control.element.querySelector('.control-content');
+
+            content.innerHTML = `
+                <div style="padding: 1rem; font-size: 0.8rem;">
+                    <h4 style="margin-top: 0;">Edit Tools</h4>
+
+                    <div style="margin-bottom: 1rem;">
+                        <button onclick="window.print()"
+                                style="width: 100%; padding: 0.5rem; margin-bottom: 0.5rem; background: #28a745; color: white; border: none; border-radius: 3px; cursor: pointer; font-size: 0.8rem;">
+                            🖨️ Print Document
+                        </button>
+
+                        <button onclick="navigator.clipboard?.writeText(window.location.href) || prompt('Copy this URL:', window.location.href)"
+                                style="width: 100%; padding: 0.5rem; margin-bottom: 0.5rem; background: #17a2b8; color: white; border: none; border-radius: 3px; cursor: pointer; font-size: 0.8rem;">
+                            📋 Copy Link
+                        </button>
+
+                        <button onclick="window.scrollTo({top: 0, behavior: 'smooth'})"
+                                style="width: 100%; padding: 0.5rem; margin-bottom: 0.5rem; background: #6c757d; color: white; border: none; border-radius: 3px; cursor: pointer; font-size: 0.8rem;">
+                            ⬆️ Scroll to Top
+                        </button>
+                    </div>
+
+                    <div style="margin-top: 1rem; font-size: 0.7rem; color: #666; border-top: 1px solid #dee2e6; padding-top: 0.5rem;">
+                        <strong>Page Info:</strong><br>
+                        Title: ${document.title}<br>
+                        Words: ~${(document.body.textContent || '').split(/\\s+/).filter(w => w.length > 0).length}<br>
+                        Modified: ${document.lastModified}
+                    </div>
+                </div>
+            `;
+            this.control.isExpanded = true;
+        };
+
+        this.control.toggle = () => {
+            if (this.control.isExpanded) {
+                this.control.element.querySelector('.control-content').style.display = 'none';
+                this.control.isExpanded = false;
+            } else {
+                this.control.buildContent();
+                this.control.element.querySelector('.control-content').style.display = 'block';
+            }
+        };
+    }
+
+    createControl() {
+        return this.control.createControl();
+    }
+}
+
+window.EditControl = EditControl;