fix: cpufreqd MSR spam, udev-shim PCI spam, scheme throttle, keymaps dir

- cpufreqd: suppress MSR errors after 1 failure (was 10)
- udev-shim: demote PCI scan failures from WARN to DEBUG
- accessibility/ime/keymapd: throttle EBADF loop with 100ms sleep
- config: create /etc/keymaps directory for keymapd

config/redbear-full.toml

@@ -229,6 +229,10 @@ args = ["-l", "info"]
 type = "oneshot_async"
 """
 
+[[files]]
+path = "/etc/keymaps/.gitkeep"
+data = ""
+
 [[files]]
 path = "/etc/init.d/13_redbear-keymapd.service"
 data = """