Phase 5: Configuration & Documentation

Updated all documentation and configuration files:

Documentation changes:
- Updated README.md to describe LLMX as LiteLLM-powered fork
- Updated CLAUDE.md with LiteLLM integration details
- Updated 50+ markdown files across docs/, llmx-rs/, llmx-cli/, sdk/
- Changed all references: codex → llmx, Codex → LLMX
- Updated package references: @openai/codex → @llmx/llmx
- Updated repository URLs: github.com/openai/codex → github.com/valknar/llmx

Configuration changes:
- Updated .github/dependabot.yaml
- Updated .github workflow files
- Updated cliff.toml (changelog configuration)
- Updated Cargo.toml comments

Key branding updates:
- Project description: "coding agent from OpenAI" → "coding agent powered by LiteLLM"
- Added attribution to original OpenAI Codex project
- Documented LiteLLM integration benefits

Files changed: 51 files (559 insertions, 559 deletions)

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

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

.github/pull_request_template.md

@@ -1,7 +1,7 @@
 # External (non-OpenAI) Pull Request Requirements
 
 Before opening this Pull Request, please read the dedicated "Contributing" markdown file or your PR may be closed:
-https://github.com/openai/codex/blob/main/docs/contributing.md
+https://github.com/valknar/llmx/blob/main/docs/contributing.md
 
 If your PR conforms to our contribution guidelines, replace this text with a detailed and high quality description of your changes.