Ensures data directory is ignored

Adds `data/` to the `.gitignore` to prevent local, transient, or sensitive data files from being committed to the repository. This change is applied both directly to the project's `.gitignore` and programmatically through the `init` command, standardizing its exclusion for new projects.

Author: defuj

.gitignore

@@ -9,3 +9,4 @@ template
 .npmignore
 .opencode/config.json
 .opencode/config.*.json
+data/

bin/commands/init.mjs

@@ -250,6 +250,7 @@ export async function init(options) {
     ".opencode/*",
     "opencode.json",
     "opencode.example.json",
+    "data/",
   ];
   if (!existsSync(gitignorePath)) {
     writeFileSync(gitignorePath, gitignoreEntries.join("\n") + "\n", "utf-8");