feat: Thin Empowerment Layer & AI Grounding Unification

[fqjony]

🧩 Overview

This PR implements the Thin Empowerment Layer refactor, unifying AI orchestration and repository-bound engineering logic into a deterministic, context-driven framework.

🚀 Key Changes

• CLI Unification: Purged legacy commands (codex, exec, prompt) in favor of first-class primitives: sync, visualizer, task, and ai.
• Dynamic Discovery Engine: Implemented a convention-based discovery system that scans script headers and SKILL.md files, eliminating static YAML mappings.
• Skill Mesh Expansion: Integrated high-fidelity discovery for GitHub repositories, NPM packages, and Context7 library context.
• AI Grounding Layer: Re-installed Gemini and Codex integrations with mandatory safety mandates and repository-centric grounding.
• Unified Repository Hub: Established .udx/dev.kit as the hidden, repository-scoped hub for all state and configuration.
• Graceful Empowerment: Refactored doctor and status to provide proactive environment hydration advice and high-signal engineering briefs.
• Cleanup & Optimization: Purged the redundant capture feature, legacy documentation, and fragmented logic to maintain a lean, high-fidelity source tree.

✅ Verification

• Validated via dev.kit doctor and dev.kit skills list.
• Tested the Dynamic Discovery Engine with virtual skills (gh, npm, docker).
• Verified atomic sync grouping across all core domains.