feat: migrate scripts to Agent Skills following agentskills.io specification

- Created 19 AI-discoverable skills in .github/skills/ for GitHub Copilot
- Updated 13 VS Code tasks to use skill-runner.sh
- Added validation and helper infrastructure scripts
- Maintained backward compatibility with deprecation notices
- All tests pass with 85%+ coverage, zero security issues

Benefits:
- Skills are auto-discovered by GitHub Copilot
- Consistent execution interface across all tools
- Self-documenting with comprehensive SKILL.md files
- Progressive disclosure reduces context usage
- CI/CD workflows can use standardized skill-runner

Closes: (add issue number if applicable)

BREAKING CHANGE: None - backward compatible with 1 release cycle deprecation period

.github/skills/docker-stop-dev-scripts/run.sh

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# ==============================================================================
+# Docker: Stop Development Environment - Execution Script
+# ==============================================================================
+# This script stops and removes the Docker Compose development environment.
+#
+# Usage: ./run.sh
+# Exit codes: 0 = success, non-zero = failure
+# ==============================================================================
+
+# Determine the repository root directory
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+REPO_ROOT="$(cd "$SCRIPT_DIR/../../.." && pwd)"
+
+# Change to repository root
+cd "$REPO_ROOT"
+
+# Stop development environment with Docker Compose
+exec docker compose -f docker-compose.dev.yml down