Migrate from Claude Code to OpenCode structure

- Move legacy content to legacy/ folder (old, old2, docs, learnings, scripts)
- Create new .opencode/ structure with skills/, tools/, agents/ folders
- Update Makefile to symlink to ~/.config/opencode/ instead of ~/.claude/
- Update Makefile to manage skills, tools, and agents (remove settings.json)
- Simplify install/uninstall (no backup logic)
- Add README.md documenting the new structure
- Keep settings.json as historical reference

legacy/old2/skills/worktrees/scripts/create-worktree.sh

@@ -0,0 +1,74 @@
+#!/bin/bash
+set -euo pipefail
+
+# Create a git worktree for issue work or PR review
+#
+# Usage:
+#   ./create-worktree.sh issue <issue-number>
+#   ./create-worktree.sh review <pr-number> <branch-name>
+#
+# Returns: Absolute path to created worktree (stdout)
+
+MODE="$1"
+REPO_PATH=$(git rev-parse --show-toplevel 2>/dev/null || pwd)
+REPO_NAME=$(basename "$REPO_PATH")
+WORKTREES_DIR="${REPO_PATH}/../worktrees"
+
+# Ensure worktrees directory exists
+mkdir -p "$WORKTREES_DIR"
+
+# Fetch latest from origin
+cd "$REPO_PATH"
+git fetch origin >/dev/null 2>&1
+
+case "$MODE" in
+  issue)
+    ISSUE_NUMBER="$2"
+    WORKTREE_NAME="${REPO_NAME}-issue-${ISSUE_NUMBER}"
+    WORKTREE_PATH="${WORKTREES_DIR}/${WORKTREE_NAME}"
+
+    # Get issue title for branch name (tea issues output has title on line 2: "  # #1 Title here")
+    ISSUE_TITLE=$(tea issues "$ISSUE_NUMBER" 2>/dev/null | sed -n '2p' | sed 's/.*#[0-9]* //' | xargs || echo "untitled")
+
+    # Create safe branch name
+    BRANCH_NAME="issue-${ISSUE_NUMBER}-$(echo "$ISSUE_TITLE" | tr '[:upper:]' '[:lower:]' | tr ' ' '-' | tr -cd '[:alnum:]-' | cut -c1-50)"
+
+    # Remove worktree if it already exists
+    if [ -d "$WORKTREE_PATH" ]; then
+      git worktree remove "$WORKTREE_PATH" --force 2>/dev/null || true
+    fi
+
+    # Delete branch if it exists
+    git branch -D "$BRANCH_NAME" 2>/dev/null || true
+
+    # Create worktree with new branch from main
+    git worktree add "$WORKTREE_PATH" -b "$BRANCH_NAME" origin/main >/dev/null 2>&1
+
+    echo "$WORKTREE_PATH"
+    ;;
+
+  review)
+    PR_NUMBER="$2"
+    BRANCH_NAME="$3"
+    WORKTREE_NAME="${REPO_NAME}-review-${PR_NUMBER}"
+    WORKTREE_PATH="${WORKTREES_DIR}/${WORKTREE_NAME}"
+
+    # Remove worktree if it already exists
+    if [ -d "$WORKTREE_PATH" ]; then
+      git worktree remove "$WORKTREE_PATH" --force 2>/dev/null || true
+    fi
+
+    # Create worktree from existing branch
+    git worktree add "$WORKTREE_PATH" "origin/${BRANCH_NAME}" >/dev/null 2>&1
+
+    echo "$WORKTREE_PATH"
+    ;;
+
+  *)
+    echo "Error: Invalid mode '$MODE'. Use 'issue' or 'review'" >&2
+    echo "Usage:" >&2
+    echo "  $0 issue <issue-number>" >&2
+    echo "  $0 review <pr-number> <branch-name>" >&2
+    exit 1
+    ;;
+esac