fix: correct installation script URLs from ddx-tools/ddx to easel/ddx

[mehdipiraee]

Summary

Fixed all broken repository URLs throughout the codebase that were returning 404 errors.

Problem

Multiple files referenced ddx-tools/ddx repository which doesn't exist, causing 404 errors when users try to install DDx or access documentation links:

curl -fsSL https://raw.githubusercontent.com/ddx-tools/ddx/main/install.sh | bash
# Returns: 404 Not Found

Solution

Performed comprehensive update of all repository references to point to the correct repository easel/ddx:

Files Updated (15 total):

Documentation (9 files):

• README.md - Fixed installation commands and repository references
• docs/SETUP_GUIDE.md - Fixed installation URLs and GitHub links
• docs/helix/02-design/architecture.md - Updated architecture diagrams
• docs/helix/02-design/contracts/CLI-001-core-commands.md - Fixed CLI contract examples
• docs/helix/02-design/contracts/CLI-002-sync-commands.md - Updated sync command examples
• docs/helix/02-design/contracts/CLI-003-utility-commands.md - Fixed utility command references
• docs/helix/02-design/data-design.md - Updated data model examples
• docs/helix/02-design/deployment.md - Fixed deployment installation instructions
• docs/helix/02-design/solution-designs/SD-002-upstream-synchronization.md - Updated sync design

Go Source Code (6 files):

• cli/cmd/contribute.go - Fixed pull request URL generation
• cli/cmd/e2e_test.go - Updated test configuration examples
• cli/cmd/sync_acceptance_test.go - Fixed acceptance test configs
• cli/cmd/sync_contract_test.go - Updated contract test examples
• cli/cmd/test_harness.go - Fixed test harness repository references
• cli/cmd/uninstall.go - Updated uninstall message URLs

Verification

Before (404 errors):

curl -I https://raw.githubusercontent.com/ddx-tools/ddx/main/install.sh
# HTTP/2 404

After (working):

curl -I https://raw.githubusercontent.com/easel/ddx/main/install.sh  
# HTTP/2 200

Test Plan

• Verified all new URLs return 200 OK
• Confirmed install.sh exists at correct location
• Tested installation command works correctly
• All repository links now point to existing repository
• Comprehensive search confirms no remaining ddx-tools/ddx references
• Go source code compiles without URL-related errors
• Documentation links are accessible

Impact

This fix resolves:

• ❌ 404 errors during DDx installation
• ❌ Broken links in documentation
• ❌ Invalid repository references in CLI output
• ❌ Incorrect test configurations
• ❌ Dead links in deployment guides

Now provides:

• ✅ Working installation command
• ✅ Accessible documentation links
• ✅ Correct repository references throughout
• ✅ Valid test configurations
• ✅ Functional deployment instructions

🤖 Generated with Claude Code