UX-13 P5: Dutch text, STYLE check, DOCS screenshots, period editor

- app/ui_text/nl.json and app/uitext.py: every page word in Dutch, English
  fallback per key; the page picks by browser language. Home's sentences
  move into ui_text `home_words`, so /status?lang=nl builds them in Dutch.
- test_ui_text.py: EN/NL key and placeholder parity, STYLE limits, jargon
  lists for both languages, no inline details, untranslated Dutch caught.
  Shared rules moved unchanged to tools/style_rules.py.
- tools/ux13_screenshots.sh/.py: DOCS screenshots from the demo fixtures in
  headless Chromium; docs/img/ux13/. Battery modes (P3): no screenshot.
- "Other time windows": a list editor (ui.periods) that builds
  static_profile and names bad times, empty prices, overlaps and gaps.

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

goodwe_controller/DOCS.md

@@ -2886,6 +2886,12 @@ works under hourly pricing is an EMS for a minority. `static_profile` is how a
 two-period day/night tariff or a single fixed price becomes a first-class
 configuration rather than "turn the price feature off and hope".
 
+On the add-on page, choose **Other time windows** under Settings, Tariff and
+prices, or in Setup step 4. Add one row per time window, with its start, end,
+days and price. The page names any overlap, gap or empty price before you can
+save. You only need the JSON below for days the page cannot choose, such as
+Monday and Wednesday only.
+
 It is one option, holding a JSON object, on one line:
 
 ```json
@@ -3221,6 +3227,18 @@ action log (`Controller.events`). The page no longer shows that log, but the
 page and add `status` to its address. The action-log tables in this document
 refer to it.*
 
+### Language and screenshots
+
+The page is in Dutch when your browser's language is Dutch, and in English
+otherwise. Status lines, alarms and the start checks' messages stay in English.
+
+Screenshots of each screen are in the add-on's repository, under
+`docs/img/ux13/`. The battery-mode screens are not built yet, so there are no
+screenshots of them.
+
+*For installers: regenerate the screenshots with
+`tools/ux13_screenshots.sh`, which serves the page from test fixtures.*
+
 ### Setup, for a new install
 
 The **Setup** tab walks an installer through six steps: the meter, the