feat: add bash shell completions (#6239)

packages/opencode/src/index.ts

@@ -77,6 +77,7 @@ const cli = yargs(hideBin(process.argv))
     })
   })
   .usage("\n" + UI.logo())
+  .completion("completion", "generate shell completion script")
   .command(AcpCommand)
   .command(McpCommand)
   .command(TuiThreadCommand)