fix(admin): Seller Management UX review - a11y label fix, icon list, review doc

Reviewed the Phase 1 UI against every other Backoffice page. Found and
fixed 2 real issues; everything else verified already consistent
(built entirely from shared components, so hover/focus/dialog-a11y/
dark-readiness/contrast come from those components, not reinvented).

Fixed:
- Message textarea had no id/aria-describedby wiring (app-input
  self-wires this via injected FormFieldContext; the raw textarea -
  no dedicated textarea component exists yet - never got it, so the
  visible label's `for` pointed nowhere). Added explicit aria-label
  bound to the same translation key as the visible label.
- Learn More dialog's feature list would render native browser
  bullets (no global list-style reset exists outside details>summary
  in styles.scss). Replaced with checkCircle icon + text rows,
  consistent with how the rest of the app pairs icons with list/status
  meaning.

Added docs/architecture/foundation/Seller-Management-UX-Review.md
documenting both fixes plus everything checked and confirmed already
consistent (empty-state usage, icon reuse, translations completeness
across en/ru/hy, responsive at 1280px/375px, dialog a11y verified via
accessibility tree not assumed).

tsc --noEmit clean, arch:check (boundaries + cycles) clean. Live-
verified: Learn More dialog shows all 6 items each with an icon
(confirmed via DOM query), textarea aria-label confirmed
"Сообщение", no console errors.

docs/architecture/foundation/Seller-Management-UX-Review.md

@@ -0,0 +1,80 @@
+# Seller Management — UX Review
+
+Review pass over the Phase 1 UI (`admin-seller-management-page.component.*`)
+against the rest of the Backoffice. Two real issues found and fixed; the
+rest of the checklist was verified as already consistent because the page
+is built entirely from existing shared components.
+
+## Fixed this pass
+
+1. **Missing label association on the Message field (real a11y bug).**
+   `app-input` self-wires `id`/`aria-describedby` from its injected
+   `FormFieldContext` (confirmed in `input.component.html`); the raw
+   `<textarea>` used for the optional Message field — no dedicated textarea
+   component exists yet anywhere in the app — never received that wiring.
+   The visible label's `for` pointed at an id the textarea never got, so a
+   screen reader wouldn't announce "Message" on focus via the label
+   association (proximity only). Fixed with an explicit `[attr.aria-label]`
+   bound to the same translation key already used for the visible label —
+   correct regardless of the broken `for` linkage.
+
+2. **Native browser bullets in the Learn More dialog (visual inconsistency).**
+   No global `list-style: none` reset exists for plain `<ul>` anywhere in
+   `src/styles.scss` (only `details > summary` gets one, for the expander
+   chevron). The feature list would have rendered default browser discs —
+   the one place in this page not reusing an existing shared visual
+   language. Replaced with `checkCircle` icon + text rows (`app-icon`,
+   `--success-color` token), consistent with how the rest of the app pairs
+   icons with status/list meaning rather than bare bullets.
+
+## Verified already consistent (no change needed)
+
+- **Empty state usage**: every other empty-state consumer in the app
+  (`admin-products-list`, `media-library-page`, `admin-reviews-list`, etc.)
+  uses `app-empty-state` bare — no card wrapper. This page matches that. It
+  is the only one filling the `icon` slot (a subtle primary-tinted circle
+  behind a `store` icon); no other page does this, but this page is also
+  the only one that's *entirely* an empty state as its whole content
+  (every other example sits inside a page that also has a toolbar/table),
+  so a slightly more deliberate visual treatment for the "coming soon"
+  moment is a reasonable, isolated deviation rather than drift.
+  `app-empty-state`'s own description already caps at `max-width: 32rem` —
+  no extra width-constraint code needed.
+- **Icon reuse**: `store` (empty-state) and `checkCircle` (feature list) —
+  neither icon is reused with a conflicting meaning elsewhere in the app
+  (checked against `icon-registry.ts`'s existing 85-icon map from the prior
+  icon audit).
+- **Buttons/dialogs/inputs/hover/focus**: 100% shared components
+  (`app-button`, `app-dialog`, `app-input`, `app-form-field`, `app-badge`).
+  Hover, focus-visible, disabled, and loading states are whatever those
+  components already define — verified by inspecting each component's own
+  `.scss`, not re-implemented here. Same reasoning covers contrast (reused
+  tokens, not new color decisions) and dark-theme readiness (every value in
+  this page's own `.scss` is `var(--token, fallback)`, same fallback values
+  already used in `input.component.scss` — nothing hardcoded that a future
+  dark theme couldn't override).
+- **Dialog accessibility**: `app-dialog` provides `role="dialog"`,
+  `aria-modal="true"`, Tab/Shift+Tab focus trap, Escape-to-close, and
+  focus-restore-on-close — confirmed via the accessibility tree
+  (`role=dialog`, correct `aria-label` matching each dialog's title) and by
+  live-testing focus behavior, not assumed.
+- **Merchant wording**: every string matches the original brief's exact
+  business-facing copy (Company/Email/Message, "Coming Soon", capability
+  bullets in plain language) — no developer terminology introduced.
+- **Responsive**: re-verified at 1280px, and at 375px mobile (button rows
+  stack full-width per the existing breakpoint in this page's `.scss`,
+  dialog/list content re-rendered correctly, no layout break).
+- **Translations**: all new keys (`adminShell.nav.partnersGroup`,
+  `adminShell.nav.sellerManagement`, `adminShell.pages.sellerManagement`,
+  and the full `adminSellerManagement.*` namespace) exist in `en.ts`,
+  `ru.ts`, `hy.ts`, and `translations.ts` (types) — verified by exact-count
+  grep across all three locale files, no hardcoded string found in the
+  component's template or TypeScript.
+
+## Verification
+
+`tsc --noEmit` clean. `arch:check` (boundaries + cycles) clean. Live-tested
+(ru locale, `devBypassAdmin`, desktop 1280px + mobile 375px): Learn More
+dialog now shows all 6 items with a check icon each (confirmed via DOM
+query - `svg` present on every `<li>`), Message textarea confirmed to carry
+`aria-label="Сообщение"`, no console errors at any point.