Fix put_status/put_error behavior (#47)

* Fix `put_status`/`put_error` behavior

- use `put_error` instead of `put_status` for command errors
- prevent status message output to console during initialization
- use `put_error` for side effects in command errors
- add `&` prefix in status messages to force screen flush
- flush screen in `qe_display()`, remove redundant calls to `dpy_flush`
- fix gcc compilation errors and warnings
- remove most references to `global_screen`
- free font cache before closing the screen
- prevent mouse handling upon focus detection

* drop CI on macos-12

.github/workflows/ci.yml

@@ -63,7 +63,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [macos-12, macos-14]
+        os: [macos-13, macos-14]
     steps:
       - uses: actions/checkout@v4
       - name: build