Add installer (#10)

* add `install_pkg_cli_apps()`

air format

* add `Rapp` installer

* add NEWS + update README with `install_pkg_cli_apps()`

* windows fixes

* more windows fixes

* Add support for plain Rscript shebangs

* add `overwrite` guardrail

Author: t-kalinowski

DESCRIPTION

@@ -13,7 +13,7 @@ URL: https://github.com/r-lib/Rapp
 BugReports: https://github.com/r-lib/Rapp/issues
 Encoding: UTF-8
 Roxygen: list(markdown = TRUE)
-RoxygenNote: 7.3.2
+RoxygenNote: 7.3.3
 Suggests: 
     testthat (>= 3.0.0)
 Config/testthat/edition: 3

NAMESPACE

@@ -4,4 +4,5 @@ S3method("$",yaml)
 S3method("[",yaml)
 S3method("[[",yaml)
 S3method(print,yaml)
+export(install_pkg_cli_apps)
 export(run)

NEWS.md

@@ -1,6 +1,9 @@
 # Rapp (development version)
 
 * Added support for short opts (#4, #5).
+* New `install_pkg_cli_apps()` helper installs launchers on the `PATH` for Rapps
+  in a package's `exec/` directory, prunes removed apps, and installs a
+  top-level `Rapp` launcher alongside them.
 
 # Rapp 0.2.0