Add git-worktree-create tool for creating git worktrees

.opencode/tools/git-worktree-create.ts

@@ -0,0 +1,15 @@
+import { tool } from "@opencode-ai/plugin"
+import { $ } from "bun"
+
+export default tool({
+  description: "Create a git worktree for a branch or PR",
+  args: {
+    branch: tool.schema.string().describe("Branch name or PR number"),
+    directory: tool.schema.string().describe("Worktree directory name (optional)"),
+  },
+  async execute(args) {
+    const worktreeDir = args.directory || args.branch
+    const result = await $`git worktree add ./worktrees/${worktreeDir} ${args.branch}`.text()
+    return result.trim()
+  },
+})