feat: implement finalized local snippet card design

[imantsk]

Implements the finalized card design for local snippets on the manage screen, building on the UI foundation branch.

Changes

• Card shell (SnippetCard): 5px corner radius, restyled footer bar split into a status region (inline start) and an actions region (inline end) via a new footerStatus prop; custom-styled 20×20 bulk-select checkbox with accent border and white check when checked.
• Card header: activation toggle, type badge, and 18px accent title on a single row. Toggle restyled to a 36×19 accent pill (transparent with accent knob when off, accent fill with white knob when on).
• Meta row: tag links at the inline start, "Modified X ago" at the inline end, followed by a separator and a two-line clamped description.
• Selection checkbox is hidden until the card is hovered or focused, and stays visible while checked or while any selection is active in the grid (including select-all).
• Footer actions: Preview (outline) and Edit (filled) buttons plus a kebab menu that replaces the previous "Show more" expander. Menu contents: Clone, Export, divider, inline Priority editor (reuses the existing save-on-blur/submit PriorityColumn; the menu stays open while editing), divider, Restore (trashed view) and Trash/Delete Permanently (destructive, existing confirmation flow).
• Extracted the delete confirmation flow from DeleteButton into a reusable useDeleteSnippet hook so the kebab menu shares it without duplication.
• Removed the .snippet-card-more* expander markup and styles.
• Network-only and shared-network snippets keep their previous capabilities: status label in the footer, no edit/clone/export/delete actions, priority still editable. Trashed snippets show Restore and Delete Permanently, matching the list-view row actions.

Verification

• npm run build — passes
• npm run lint:js — passes
• npm run lint:styles — passes
• npm run test:php — 116 tests, 258 assertions, 0 failures

[code-snippets-bot]

Three behavior-preserving cleanups remain in this PR's exact diff:

• Medium — Preserve machine-readable modified dates. src/js/components/ManageMenu/SnippetsTable/ManageSnippetCard.tsx:166-174 replaces DateColumn, which emitted <time dateTime={snippet.modified}>, with a plain <span>. Keep the card-specific “Modified …” copy, but wrap it in <time dateTime={snippet.modified}> or reuse a shared modified-date component.
• Low — Reuse the canonical capability helpers. ManageSnippetCard.tsx:24-28 duplicates isNetworkOnlySnippet() and canModifySnippet() from src/js/utils/snippets/snippets.ts:105-114. Import the shared helpers so card and table permission logic cannot drift.
• Low — Remove the newly dead corner-controls path. Moving activation into the card header leaves SnippetCard.cornerControls without callers. Remove the unused prop, conditional markup, has-corner-controls class, and related styling.

[imantsk]

Switched cards to the canonical network and modified helpers, rendered modified dates with time semantics, and removed the unused corner-control API and styles. Lint and build pass.

[code-snippets-bot]

Three semantic cleanups remain:

• The priority field is placed inside <ul role="menu"> via a role="presentation" row (KebabMenu.tsx:72-75,228-235, used at ManageSnippetCard.tsx:133-136). This leaves a focusable spinbutton inside a menu without a menu-item role, which does not conform to the ARIA menu pattern. Please either make this a generic popover with native form-control semantics or keep the menu restricted to menu items and move the priority control outside it.
• SearchResult.tsx:59-66 renders the new cloud modified date as a <span>. Please use <time dateTime={snippet.updated}>, matching the local-card fix.
• SearchResult.tsx:20-25 concatenates the translated "By " fragment with the author link. Please expose a complete, reorderable translated phrase rather than a standalone translated fragment.

[imantsk]

The kebab is now a generic popover with native form-control semantics, modified dates render as <time> elements, and the author credit is a single translatable phrase.

[sheabunge]

This is a bad pattern IMO: avoid components returning other components where possible.

[sheabunge]

Why is this removed?

[sheabunge]

Why is this removed?

[sheabunge]

Please avoid breaking imports into multiple lines – they do not need to be human readable.

[sheabunge]

Avoid nesting ternary statements where possible.