Unify ISO install orchestration

Drive installs through the common ISO pipeline, carry install intent in configurator JSON, and finalize Limine boot setup from the ISO.

README.md

@@ -1,6 +1,6 @@
 # Omarchy ISO
 
-The Omarchy ISO streamlines [the installation of Omarchy](https://learn.omacom.io/2/the-omarchy-manual/50/getting-started). It includes the Omarchy Configurator as a front-end to archinstall and automatically launches the [Omarchy Installer](https://github.com/basecamp/omarchy) after base arch has been setup.
+The Omarchy ISO is the only supported way to install Omarchy. It ships the Omarchy Configurator, installs Arch Linux, installs the Omarchy packages from the bundled mirror, runs target system setup in the chroot, creates the user, and runs `omarchy-setup-user` for that user.
 
 ## Downloading the latest ISO
 
@@ -8,20 +8,18 @@ See the ISO link on [omarchy.org](https://omarchy.org).
 
 ## Creating the ISO
 
-Run `./bin/omarchy-iso-make` and the output goes into `./release`. You can build from your local $OMARCHY_PATH for testing by using `--local-source` or from a checkout of the dev branch (instead of master) by using `--dev`.
+Run `./bin/omarchy-iso-make`; output goes into `./release`.
 
-### Environment Variables
+For local development, build the ISO from sibling checkouts:
 
-You can customize the repositories used during the build process by passing in variables:
-
-- `OMARCHY_INSTALLER_REPO` - GitHub repository for the installer (default: `basecamp/omarchy`)
-- `OMARCHY_INSTALLER_REF` - Git ref (branch/tag) for the installer (default: `master`)
-
-Example usage:
 ```bash
-OMARCHY_INSTALLER_REPO="myuser/omarchy-fork" OMARCHY_INSTALLER_REF="some-feature" ./bin/omarchy-iso-make
+./bin/omarchy-iso-make --local-source ../omarchy-installer ../omarchy-pkgs
 ```
 
+Despite the local folder name, the first argument is the Omarchy source checkout (runtime commands, configs, setup scripts, themes, shell, migrations). The installer itself lives in this ISO repo.
+
+Use `--dev` or `--rc` to build against those package channels.
+
 ## Testing the ISO
 
 Run `./bin/omarchy-iso-boot [release/omarchy.iso]`.
@@ -32,7 +30,7 @@ Run `./bin/omarchy-iso-sign [gpg-user] [release/omarchy.iso]`.
 
 ## Uploading the ISO
 
-Run `./bin/omarchy-iso-upload [release/omarchy.iso]`. This requires you've configured rclone (use `rclone config`).
+Run `./bin/omarchy-iso-upload [release/omarchy.iso]`. This requires rclone configuration (`rclone config`).
 
 ## Full release of the ISO