feat: add tea CLI pull request tools

Add three tools for managing pull requests via the tea CLI:
- tea-pulls: list pull requests filtered by state
- tea-pr-get: get PR details with comments
- tea-pr-create: create a PR with title, branch, assignees, and labels

.opencode/tools/tea-pr-get.ts

@@ -0,0 +1,13 @@
+import { tool } from "@opencode-ai/plugin"
+import { $ } from "bun"
+
+export default tool({
+  description: "Get a specific pull request with all details and comments using tea CLI",
+  args: {
+    pullNumber: tool.schema.number().describe("Pull request number/index"),
+  },
+  async execute(args) {
+    const result = await $`tea pulls ${args.pullNumber} --comments --output json`.text()
+    return result.trim()
+  },
+})