Add Linux native packaging README

Author: mdheller

packaging/linux/README.md

@@ -0,0 +1,53 @@
+# TurtleTerm Linux Native Packaging
+
+TurtleTerm is Linux-first. This directory stages native Linux package metadata after Homebrew and release tarball install paths.
+
+## Current package scaffolds
+
+- `deb/control`
+- `rpm/turtle-term.spec`
+- `arch/PKGBUILD`
+
+## Shared package layout
+
+All native package lanes should use:
+
+```bash
+packaging/scripts/stage-linux-package.sh
+```
+
+The staged layout includes:
+
+```text
+bin/turtleterm
+bin/turtleterm-mux-server
+bin/turtle-term
+bin/turtle-agentd
+bin/turtle-agentctl
+bin/turtle-tmux
+bin/sourceos-term
+etc/turtle-term/turtleterm.lua
+libexec/turtle-term/
+share/applications/ai.sourceos.TurtleTerm.desktop
+share/metainfo/ai.sourceos.TurtleTerm.metainfo.xml
+share/icons/hicolor/scalable/apps/ai.sourceos.TurtleTerm.svg
+share/turtle-term/
+```
+
+## Validation
+
+Run:
+
+```bash
+packaging/scripts/verify-linux-package-layout.sh
+```
+
+The verifier stages the package layout with stub runtime binaries and checks public commands, private runtime isolation, metadata, profile, and agent CLI behavior.
+
+## Not done yet
+
+- Real `.deb` build workflow
+- Real `.rpm` build workflow
+- Real Arch package build workflow
+- Release checksums for Arch source package
+- SourceOS image integration