chore: refactor agent configurations and update testing instructions

- Updated QA Security agent to use GPT-5.2-Codex and expanded toolset for enhanced functionality.
- Revised Supervisor agent to utilize GPT-5.2-Codex and improved toolset for code review processes.
- Modified architecture instructions to specify running Playwright tests with Firefox.
- Adjusted copilot instructions to run Playwright tests with Firefox as the default browser.
- Created documentation for coding best practices to ensure consistency and quality in project documentation.
- Established HTML/CSS style color guide to maintain accessible and professional design standards.
- Updated Playwright TypeScript instructions to reflect the change in default browser to Firefox.
- Enhanced testing instructions to clarify integration testing processes and default browser settings.
- Updated integration test scripts to align with CI workflows and improve clarity in execution.
- Created new integration test scripts for Cerberus, rate limiting, and WAF functionalities.
- Adjusted E2E testing scripts to default to Firefox and updated documentation accordingly.
- Modified GitHub Actions workflow to run the comprehensive integration test suite.

.github/instructions/copilot-instructions.md

@@ -128,7 +128,7 @@ Before proposing ANY code change or fix, you must build a mental map of the feat
 Before marking an implementation task as complete, perform the following in order:
 
 1. **Playwright E2E Tests** (MANDATORY - Run First):
-    - **Run**: `npx playwright test --project=chromium` from project root
+    - **Run**: `cd /projects/Charon npx playwright test --project=firefox` from project root
     - **Why First**: If the app is broken at E2E level, unit tests may need updates. Catch integration issues early.
     - **Scope**: Run tests relevant to modified features (e.g., `tests/manual-dns-provider.spec.ts`)
     - **On Failure**: Trace root cause through frontend → backend flow before proceeding