Update cloud-init scripts and documentation for enhanced DNS management and provisioning steps</message>

<message>Modify the first-boot.sh script to include an additional step for managing screen brightness during the provisioning process. Update user-data.bootstrap to improve DNS configuration by ensuring NetworkManager manages /etc/resolv.conf correctly, and remove obsolete scripts related to systemd-resolved. Enhance documentation to reflect these changes and clarify the setup process for users, improving overall network boot functionality and user experience.

emmc-provisioning/cloud-init/fileserver/screen-brightness.conf

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+# screen-brightness.conf — reTerminal DM Bridge Brightness Daemon
+#
+# Regulatory basis
+#   IMO MSC.191(79) §8.1  : brightness adjustable, never extinguished
+#   IMO MSC.302(87)       : alarms = high luminance; night mode preserves night vision
+#   IHO S-52 / IEC 62288  : NIGHT / DUSK / DAY operating modes
+#
+# Reload without restart: systemctl reload screen-brightness
+# Override from bridge console:
+#   echo 3    | sudo tee /run/screen-brightness/override   # fix at level 3
+#   echo auto | sudo tee /run/screen-brightness/override   # return to auto
+
+[screen-brightness]
+
+# ── Sysfs paths ──────────────────────────────────────────────────────────────
+backlight_path = /sys/class/backlight/lcd_backlight/brightness
+buzzer_path    = /sys/class/leds/usr-buzzer/brightness
+lux_path       = /sys/bus/iio/devices/iio:device0/in_illuminance_input
+
+# ── Timing ───────────────────────────────────────────────────────────────────
+# How often the ambient sensor is read (seconds)
+poll_interval = 2
+
+# How often the buzzer is checked (seconds). Keep below 1 so alarms are seen quickly.
+buzzer_poll = 0.5
+
+# How long to hold maximum brightness after the buzzer stops (seconds)
+# IMO MSC.302(87): alarm attention must persist long enough for crew response
+buzzer_cooldown = 10
+
+# ── Lux thresholds — IHO S-52 three-mode framework ──────────────────────────
+# Adjust these to match the actual lighting environment of your bridge.
+#
+#  0 — lux_night_max     → NIGHT mode  (very dark, night watch)
+#  lux_night_max+1 — lux_dusk_max  → DUSK  mode  (dim, dawn/dusk)
+#  lux_dusk_max+1  — lux_day_dim_max → DAY-DIM
+#  lux_day_dim_max+1 — lux_day_normal_max → DAY-NORMAL
+#  > lux_day_normal_max  → DAY-BRIGHT (direct sunlight / tropical day)
+
+lux_night_max      = 20
+lux_dusk_max       = 200
+lux_day_dim_max    = 500
+lux_day_normal_max = 1000
+
+# ── Brightness levels per mode (1 = minimum, 5 = maximum) ───────────────────
+# Level 0 is NEVER used — IMO "not to extinction" principle.
+# Minimum must remain legible at the navigator's position.
+level_night      = 1
+level_dusk       = 2
+level_day_dim    = 3
+level_day_normal = 4
+level_day_bright = 5
+
+# Brightness forced during ALERT (buzzer ON) and COOLDOWN states.
+# IMO MSC.302(87): alarm visual indicators must be high luminous intensity.
+level_alert = 5
+
+# ── Hysteresis ───────────────────────────────────────────────────────────────
+# Number of consecutive polls that must agree on a new ambient brightness
+# target before the change is committed. Prevents flickering when lux hovers
+# near a mode boundary (e.g. sunset making the sensor oscillate 18–22 lux).
+# At poll_interval=2s and hysteresis_polls=3, a level change takes max 6s.
+hysteresis_polls = 3