build: add guarded installation of the macOS app bundle

README.md

@@ -2,7 +2,7 @@
 
 A native macOS application launcher. Open it normally, search for an application, and press Return to open it or bring its existing instance forward. Global shortcuts are deliberately deferred.
 
-## Build and run
+## Build, run, and install
 
 Requires macOS 14 or later and a Swift 6 toolchain (Xcode 16 or later).
 
@@ -14,9 +14,18 @@ This builds a release executable, assembles an ad-hoc-signed application at `.bu
 
 ```sh
 make build   # Build the application without opening it.
-make test    # Run the discovery and search behavior tests.
+make install # Install the application at /Applications/Conjure.app.
+make test    # Run behavior and installation safety tests.
 ```
 
+`make install` rebuilds the signed bundle and installs it without launching it. To install for your user only, or if `/Applications` is not writable:
+
+```sh
+make install INSTALL_DIR="$HOME/Applications"
+```
+
+Installation verifies a temporary copy before replacing the entire existing bundle, so removed resources do not linger. Quit the app at the destination before reinstalling; other running copies are left alone. Unrelated apps and symbolic-link destinations are not replaced. Installation does not request administrator privileges, and the signature remains local/ad-hoc rather than notarized.
+
 Open `Package.swift` in Xcode to edit the project. Use the bundled app above to run it with its application identity and metadata.
 
 ## Controls