feat: add laptop/display brightness modulation

programs/data/config/capabilities.toml

@@ -3,7 +3,8 @@
 #
 # Capability names: process_admin, power_request, power_control, suspend,
 # storage_admin, raw_storage, network_admin, set_time, user_admin,
-# display_admin, device_admin, log_read, system_image, compositor and "all".
+# display_admin, device_admin, log_read, system_image, compositor, brightness
+# and "all".
 #
 
 # ==== System services (started by init) ====
@@ -26,6 +27,7 @@ delegable = [
     "power_request", "suspend", "process_admin", "storage_admin",
     "raw_storage", "network_admin", "set_time", "user_admin",
     "display_admin", "device_admin", "log_read", "compositor",
+    "brightness",
 ]
 
 [grant.sshd]
@@ -38,11 +40,12 @@ effective = [
     "power_request", "suspend", "process_admin", "storage_admin",
     "raw_storage", "network_admin", "set_time", "user_admin",
     "display_admin", "device_admin", "log_read", "compositor",
+    "brightness",
 ]
 delegable = [
     "power_request", "suspend", "process_admin", "storage_admin",
     "raw_storage", "network_admin", "set_time", "user_admin",
-    "display_admin", "device_admin", "log_read",
+    "display_admin", "device_admin", "log_read", "brightness",
 ]
 
 [grant.terminal]
@@ -68,7 +71,7 @@ delegable = ["network_admin"]
 
 [grant.display]
 path = "0:/apps/display/display.elf"
-effective = ["display_admin"]
+effective = ["display_admin", "brightness"]
 
 [grant.disks]
 path = "0:/apps/disks/disks.elf"