fix(strommix): full i18n + drop hardcoded grid constraints

Two issues from the audit:

1. Hardcoded `lg:col-span-8 lg:col-start-3` collided with the layout
   coming from `getBlockLayoutClasses(block.layout)`. Tailwind picked
   `lg:col-start-3` from the hardcoded class (no opposing
   `lg:col-start-1` in the layout output) so the widget started at
   column 3 with span 12 → overflowed past the 12-col grid on
   desktop, looking like it was "hanging right". Drop the hardcoded
   constraints; the layout config from the CMS controls width
   (mobile/tablet/desktop = 12 by default = full width).
2. Roughly 25 German strings were inline. Extracted them to
   translation keys (T.strommix_*, registered in translations.ts) and
   read via `useTranslate()` like ImageGalleryBlock /
   PostOverviewBlock / YoutubeVideoBlock. Includes field labels for
   the breakdown disclosure, source attribution variants, status
   bucket markers, error / loading / fallback messages, and the
   conventional formula text shown under the "Konventionell jetzt"
   number.

Default DE strings live in cms_content/windwiderstand/translation_bundle/
app.json5 (separate CMS push).

src/lib/translations.ts

@@ -168,6 +168,42 @@ const TRANSLATION_KEYS = [
   "post_action_copied",
   "post_action_print",
   "post_action_reading_time",
+  // Strommix-Live-Widget (StrommixBlock.svelte).
+  "strommix_header",
+  "strommix_stand",                 // {{time}}
+  "strommix_load_error",            // {{error}}
+  "strommix_loading",
+  "strommix_wind_solar_share",
+  "strommix_load_missing",
+  "strommix_conventional_now",
+  "strommix_conventional_formula",
+  "strommix_saldo",
+  "strommix_import",
+  "strommix_export",
+  "strommix_delayed",
+  "strommix_price_de",              // {{price}}
+  "strommix_price_fr_inline",       // {{price}}
+  "strommix_slot",                  // {{time}}
+  "strommix_negative_price",
+  "strommix_check_values",
+  "strommix_field_wind_onshore",
+  "strommix_field_wind_offshore",
+  "strommix_field_solar",
+  "strommix_field_lignite",
+  "strommix_field_hard_coal",
+  "strommix_field_gas",
+  "strommix_field_nuclear",
+  "strommix_field_biomass",
+  "strommix_field_hydro",
+  "strommix_field_load",
+  "strommix_source",
+  "strommix_source_smard",
+  "strommix_source_hybrid",
+  "strommix_source_energy_charts",
+  "strommix_source_resolution",     // {{time}}
+  "strommix_conventional_explanation",
+  "strommix_stored_data",
+  "strommix_how_calculated",
 ] as const;
 
 export type TranslationKey = (typeof TRANSLATION_KEYS)[number];