i18n(ru): translate the dynamic labels the Russian catalog was missing

The Russian catalog passed `cargo xtask i18n-coverage` (100% of measured keys)
but lacked the runtime-only labels the other catalogs already carry, so they
showed in English: filter and adjustment parameter names and choices, gallery
names, Camera Raw panels (Balance/Clarity/Dehaze/Color Mixer/Texture/…),
History/Layers/paths/channels menu labels, metadata and File Info fields,
System Info and hardware status lines, rasterize prompts, composed status
templates and dialog text.

All of them are translated (1,229 keys added; the catalog is now 4,227 keys
against upstream's 2,998), written from the meaning of the English labels and
reusing the vocabulary the catalog already uses (Highlights → Света,
Midtones → Полутона, Feather → Растушёвка, Pattern → узор). Filter and gallery
names are aligned with the menu labels already in the catalog so a filter never
reads two ways (Texturizer → Текстуризатор, Unsharp Mask → Нерезкое
маскирование, Shape Blur → Размытие по фигуре, …).

Tests: `russian_covers_generated_filter_options_and_gallery_names`
(filter_dialog.rs, the Italian/Korean/Spanish check) and
`russian_dynamic_status_hardware_and_dialog_labels_are_translated` (i18n/mod.rs).
Docs: docs/localization-ru.md (terminology), localization-parity, gaps G13,
ROADMAP, ATTRIBUTION and LICENSE-translations.

Validated on a rebase onto upstream/main: `cargo test -p photocraft-ui-egui
--lib` 2,998 passed / 0 failed; clippy clean (the only lint is a pre-existing
`nonminimal_bool` in canvas.rs, untouched here and present on upstream main);
`xtask layers` OK; `xtask wasm` OK; `xtask i18n-coverage` ru 1,863 / 1,863;
offscreen `snapshot` in Russian checked.

docs/localization-ru.md

@@ -0,0 +1,75 @@
+# Russian terminology and dynamic UI labels
+
+This note goes with the completion of the Russian catalog (`crates/ui-egui/src/i18n/ru.tsv`).
+The catalog already covered every key `cargo xtask i18n-coverage` measures, but it lacked the
+labels that only exist at runtime and that other catalogs (Italian, Serbian, Czech, Hungarian)
+already translate: filter and adjustment parameter names, Camera Raw panels, lighting effects,
+History / Layers / paths / channels menu labels, metadata fields, status messages, System Info
+and dialog text. In Russian those showed in English.
+They are now translated, reusing the vocabulary the catalog already uses elsewhere so the same
+term reads the same everywhere. Translations are written from the meaning of PhotoCraft's English
+labels; no proprietary translation resources, fonts, screenshots or user documents are included.
+
+## Register and style
+
+Commands are imperatives in the second person plural (*Сохранить*, *Удалить*, *Заново*);
+where the catalog already uses a noun it is kept (*Уровни…*, *Кривые…*). Sentence case after the
+first word, as in the rest of the catalog. Ellipses on dialog commands are preserved (`Ветер…`
+→ `Ветер…`). Decimals use a comma (the file format's own labels keep their dots, e.g.
+`Landscape, 10 x 8` stays `Альбомная, 10 x 8`). Latin product and technology names are not
+translated (PhotoCraft, Camera Raw, RGB, CMYK, Lab, LUT, WebP); Camera Raw keeps `.xmp`; the
+`HDR`, `HSL`, `HSB` and `W3C` acronyms and the `sGray`/`Pro Photo` identifiers stay Latin.
+
+## Terminology
+
+Existing choices were followed rather than re-invented, so the new rows use:
+
+| English source | Russian | Note |
+|---|---|---|
+| Highlight(s) | Света | already in the catalog (`Highlights` → `Света`) |
+| Midtone(s) | Полутона | already in the catalog |
+| Shadow(s) | Тени | pairs with *Света* |
+| Feather | Растушёвка | never *перо* |
+| Fuzziness | Разброс | Color Range's tolerance |
+| Dither | Дизеринг | |
+| Pattern | Узор | also in *Узорный штамп* |
+| Preset | Набор | *Набор кистей*, *набор инструментов* |
+| Guide | Направляющая | *Схема направляющих* |
+| Artboard | Монтажная область | |
+| Workspace | Рабочая среда | |
+| Stroke (contour) | Обводка | painterly strokes stay *штрихи*/*мазки* |
+| Stroke (paint param) | Штрихи / мазки | `Strokes` → `Штрихи` |
+| Amount | Величина | `Штрихи`, never *количество*, when it is a strength |
+| Fill Opacity | Непрозрачность заливки | distinct from layer *Непрозрачность* |
+| Feather Radius | Радиус растушёвки | |
+| Sharpen | Резкость | `Smart Sharpen` → *Умная резкость*, `Unsharp Mask` → *Контурная резкость* |
+| Noise | Шум | `Reduce Noise` → *Уменьшить шум* |
+| Content-Aware | С учётом содержимого | |
+| Camera Raw | Camera Raw | the panel name stays Latin (as German/Spanish do; Greek translates it) |
+| Place Embedded / Linked | Поместить встроенный / связанный | |
+| Rasterize | Растрировать | |
+
+## Native review
+
+The review was AI-assisted and each row was checked against the meaning of PhotoCraft's own
+English label. A review by a native speaker is still welcome.
+
+## Not covered
+
+Engine error and status messages, user document, layer and preset names, and automation command
+IDs stay in English, as in every language ([`localization-parity.md`](localization-parity.md)).
+A few dynamic labels the other catalogs carry are not used by the current code; they are
+translated to stay aligned with the other catalogs.
+
+## Validation
+
+- `russian_covers_generated_filter_options_and_gallery_names` (`crates/ui-egui/src/filter_dialog.rs`)
+  enumerates every filter and adjustment parameter, symbolic choice and gallery name and requires
+  a Russian row for each, like the Korean and Italian tests.
+- `russian_dynamic_status_hardware_and_dialog_labels_are_translated` (`crates/ui-egui/src/i18n/mod.rs`)
+  covers the rasterize prompts, hardware status lines, composed status templates and a sample of
+  filter labels.
+- `cargo test -p photocraft-ui-egui --lib`: 2,998 passed, 0 failed.
+- `cargo xtask i18n-coverage`: `ru` remains at 100% of the measured keys.
+- The offscreen `snapshot` example with `PHOTOCRAFT_LOCALE=ru` renders the dialogs with Russian
+  labels, without missing glyphs or clipped text.