feat: Linux packaging, SDK v0.7.1, fix rawmode conflict

- go.mod: SDK pseudo-version -> v0.7.1 (remote tag), go.sum updated
- cmd/waiter/rawmode_linux.go: remove (conflicts with raw_unix.go)
- cmd/gui/package.json: add rpm/AppImage Linux targets
- package/package-linux.sh: cross-distro packaging script (deb/tar.gz/rpm)
- package/linux/: DEBIAN control files, postinst/prerm, RPM spec

package/linux/deb/control-client

@@ -0,0 +1,18 @@
+Package: homeagent-client
+Version: VERSION_PLACEHOLDER
+Architecture: ARCH_PLACEHOLDER
+Maintainer: HomeAgent Team <team@homeagent.ai>
+Installed-Size: INSTALLED_SIZE_PLACEHOLDER
+Depends: libc6 (>= 2.28)
+Section: utils
+Priority: optional
+Homepage: https://github.com/trueagent/HomeAgent
+Description: HomeAgent Client (CLI + GUI, no daemon)
+ HomeAgent is a personal AI home assistant that integrates
+ large language models with system automation.
+ .
+ This package includes the client components:
+  - waiter: command-line client
+  - homeagent-gui: desktop graphical interface
+ .
+ This variant connects to a remote HomeAgent server.