Light the chamber at startup; firmwareExe is not there to do it

printer.base.cfg declares [led chamber_led] on white_pin PB5 and stops
there. Klipper's led module defaults initial_WHITE to 0, and nothing in
the mod ever set it: switching the light was firmwareExe's job, done
from its own UI, and that binary is precisely what this mod replaces.
The result is a chamber that stays dark forever and reads as a dead
lamp rather than a missing command.

Fixed by overriding the one option instead of restating the section.
Klipper parses with RawConfigParser(strict=False), so a second
[led chamber_led] merges into the first and white_pin carries over.
That is what keeps FlashForge's printer.base.cfg byte-for-byte -- it is
shipped verbatim and bin/unpack.sh warns when it differs from the stock
package -- so the pin stays theirs and only the initial value is ours.
ff-chamber.cfg is included after printer.base.cfg, which is what makes
the override land at all.

Verified against the parser rather than assumed: reading the two files
in order with klippy/configfile.py's exact RawConfigParser settings
leaves white_pin PB5 and hardware_pwm False intact alongside
initial_white 1.0, and getfloat('initial_WHITE') finds it despite
configparser folding the key to lower case.

The file grew a second subject, so its title line says so now.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

payload/klipper/config/ff-chamber.cfg

@@ -2,7 +2,7 @@
 # territorial integrity and my support for UN GA resolution ES-11/1.
 
 # ---------------------------------------------------------------------------
-# ff-chamber.cfg -- chamber heater for Mainsail prints, off on the Creator 5
+# ff-chamber.cfg -- the chamber: heater (gated by model) and light
 #
 # The Creator 5 Pro has a chamber heater; the plain Creator 5 does not. The
 # two models ship the SAME Klipper tree -- printer.base.cfg declares
@@ -96,3 +96,29 @@ gcode:
     {% if target > 0 and 'heater_generic chamber_heater' in printer %}
         TEMPERATURE_WAIT SENSOR="heater_generic chamber_heater" MINIMUM={target - ff.wait_band|float}
     {% endif %}
+
+# ---------------------------------------------------------------------------
+# The chamber light, on at startup.
+#
+# printer.base.cfg declares [led chamber_led] (white_pin PB5) and stops there.
+# Klipper's led module defaults initial_WHITE to 0, so a freshly started
+# Klipper leaves the light OFF and nothing ever turns it on: switching it was
+# firmwareExe's job, from its own UI, and that binary is what this mod
+# replaces. On stock firmware the app lit it; here the chamber simply stayed
+# dark, which reads as a broken lamp rather than a missing command.
+#
+# Overriding one option rather than restating the section: Klipper parses with
+# RawConfigParser(strict=False), so a second [led chamber_led] MERGES into the
+# first and white_pin carries over from printer.base.cfg. That matters because
+# printer.base.cfg is FlashForge's file verbatim -- bin/unpack.sh compares it
+# against every stock package and warns when it differs -- so the pin stays
+# where FlashForge put it and only the initial value is ours. This file is
+# included after printer.base.cfg, which is what makes the override land.
+#
+# To drive it by hand, or from a macro of your own:
+#     SET_LED LED=chamber_led WHITE=1     ; on
+#     SET_LED LED=chamber_led WHITE=0     ; off
+# Set initial_WHITE back to 0 for a machine that should boot dark.
+# ---------------------------------------------------------------------------
+[led chamber_led]
+initial_WHITE: 1.0