feat: fix contents panel scrollbar and consolidate control architecture

## Major Changes
- Fixed contents panel scrollbar behavior to only span content area when reaching max-height
- Eliminated duplicate control files across testdrive-jsui/static/ and markitect/static/
- Consolidated all control files to single source of truth in capabilities/testdrive-jsui/js/controls/
- Refactored contents control to use proper base class architecture

## Technical Details
- Moved overflow-y: auto from control-content-container to control-content-body
- Updated all HTML templates and plugin references to use capabilities/ paths
- Enhanced resize handle positioning (moved from -4px to 1px/2px from right edge)
- Improved CSS flex layout with proper min-height: 0 constraints

## Files Affected
- 10 duplicate control files removed
- 8+ reference files updated with new paths
- CHANGELOG.md updated with all changes

This eliminates confusion about which files to edit and ensures the UI
behaves correctly when panels reach viewport height limits.

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

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

CHANGELOG.md

@@ -7,6 +7,17 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+- Enhanced control panel UI with better resize handle positioning for improved user interaction
+
+### Changed
+- Refactored contents control architecture to use base class pattern properly for better code organization
+- Updated all file references and paths to point to single source of truth in capabilities/testdrive-jsui/js/controls/ directory
+
+### Fixed
+- Duplicate file structure issue by eliminating duplicate control files and consolidating to capabilities/ directory
+- Contents panel scrollbar behavior - moved overflow-y: auto to correct container level so scrollbar only spans content area when panel reaches max-height
+
 ### Removed
 - **BREAKING**: Legacy DocumentControls component from TestDrive JSUI plugin system - all control panel functionality now provided by enhanced control panels (ContentsControl, StatusControl, DebugControl, EditControl) with Reset All button functionality moved to EditControl for better maintainability and elimination of code duplication
 

capabilities/testdrive-jsui/js/controls/control-base.js

@@ -763,17 +763,22 @@ class ControlBase {
             content.innerHTML = `
                 <div class="control-content-container" style="
                     flex: 1;
-                    overflow-y: auto;
+                    display: flex;
+                    flex-direction: column;
                     margin: 0 0 10px 1rem;
                     padding: 0.75rem 1rem 1rem 0;
                     font-size: 0.8rem;
                     box-sizing: border-box;
                     min-height: 0;
                     border-radius: 0 0 6px 6px;
+                    overflow: hidden;
                 ">
                     <div class="control-content-body" style="
+                        flex: 1;
+                        overflow-y: auto;
                         padding: 0;
                         margin-bottom: 0;
+                        min-height: 0;
                     ">
                         ${innerContent}
                     </div>