refactor: move bundled skills tree to repo root skills/

- Relocate runtime/skills -> skills/; runtime_skills_root() prefers oclaw/skills
  with fallback to legacy runtime/skills for unmigrated trees.
- session-bootstrap hook handler resolves repo root via PROJECT_ROOT.
- Update architecture/migration docs and in-tree skill references.

Co-authored-by: Cursor <cursoragent@cursor.com>

runtime/skills/tavily-search-pro/install.sh

@@ -1,30 +0,0 @@
-#!/usr/bin/env bash
-# Tavily Search skill installer
-set -euo pipefail
-
-SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-echo "📦 Installing Tavily Search skill..."
-
-# Install Python dependencies
-pip install --break-system-packages --quiet tavily-python 2>/dev/null || {
-    echo "⚠️  pip install failed, trying without --break-system-packages..."
-    pip install --quiet tavily-python 2>/dev/null || {
-        echo "❌ Failed to install tavily-python. Install manually: pip install tavily-python"
-        exit 1
-    }
-}
-
-# Verify API key
-if [ -z "${TAVILY_API_KEY:-}" ]; then
-    echo "⚠️  TAVILY_API_KEY not set. Set it in OpenClaw config before using."
-else
-    echo "✅ TAVILY_API_KEY found"
-fi
-
-# Quick smoke test
-if python3 "$SCRIPT_DIR/lib/tavily_search.py" --help >/dev/null 2>&1; then
-    echo "✅ Tavily Search skill ready."
-else
-    echo "⚠️  Smoke test failed - check Python dependencies."
-    exit 1
-fi