LRC-LIB-SMARTCOLL: own labels for treatment Color and label None

From review: the treatment choice "Color" reused the shared "Color" key,
which zh-hans and ru translate as the colour noun (颜色, Цвет) for the
Color panel, giving "Treatment is colour". The colour-label choice
"None" was masculine in Spanish (Ninguno) next to the feminine
"etiqueta". They are now "In Color" and "No Label", translated in all
seven locales (彩色, Цветное, Sin etiqueta…).

Also moves display_label_gaps_are_reported's doc comment back onto it;
the new choice test had been inserted between them.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/whats-new.md

@@ -8,7 +8,7 @@
   Culling.
 - New fields: Keyword Count ("2 or more", "exactly 2"…), People and People Count (named faces), Shutter Speed (written
   as 1/250), File Extension, Video Duration, Copy Name, In a Stack, Alt Text, City, State / Province, Country, Long
-  Edge, Short Edge, Aspect Ratio (landscape / portrait / square), Cropped and Treatment (color / black & white).
+  Edge, Short Edge, Aspect Ratio (landscape / portrait / square), Cropped and Treatment (in color / black & white).
 - Choice values read as words in every language: "Public Domain", "Picked", "Black & White" rather than ids like
   `publicDomain` (rules and agents keep using the ids; `album.ruleFields` adds `choiceLabels`).
 - Any Searchable Text also finds the state / province, alt text, people and a virtual copy's name.