fix(web-cards): restore AT status text, guard file-link keys, add read docs

Address review of the ToolRow card refactor:
- ToolRow renders a visually-hidden run-state label (row.running/failed/stopped
  locale keys) so a running/failed/interrupted row is not a colour-only signal;
  the StateDot and the sweep are both aria-hidden. Restores the stopped-state
  text assertion in diff-card.spec at the ToolRow layer.
- The file-link button stops Enter/Space from bubbling to DisclosureRow's
  whole-row keydown, which would preventDefault the key and toggle expand
  instead of opening the file (the keyboard analogue of the click stopPropagation).
- search-row passes output={model.output} unconditionally, matching the other
  three card rows (ToolRow renders the card over the output when present).
- Assert locale: 'conversation' in the search/web/diff registration tests.
- Add the read render-intent paragraph to the ui-conversation README and a
  ReadBlock atom entry + Read section to ui-primitives (both languages).
- Update the grep fixture sample lines to the post-refactor SearchRow shape.
Refresh the code-mode-round, steering, and search-card goldens for the added
status text and updated sample lines.

apps/web/tests/snapshots/code-mode-round/ui.expected.md

@@ -24,7 +24,7 @@
   - img
   - text: Code Run bash echo and catch missing file read
 - img
-- text: Bash Echo CODE_ROUND_OK
+- text: Bash Echo CODE_ROUND_OK Failed
 - 'button "Read Error: cannot read \"{{cwd}}/workspace/missing.txt\": not found"':
   - img
   - text: "Read Error: cannot read \"{{cwd}}/workspace/missing.txt\": not found"

apps/web/tests/snapshots/search-card/grep-card.expected.txt

@@ -5,9 +5,9 @@ file=packages/client/ui-conversation/src/client/toolviews/search-row.tsx4
 line=16: export const DEFAULT_SEARCH_MAX_LINES = 16
 line=138: export function SearchBlock(props: SearchBlockProps) {
 line=141:   const [collapsed, setCollapsed] = useState<ReadonlySet<number>>(() => new Set())
-line=73:   const search = searchCardModel(block)
-line=90:         <SearchBlock {...search.card} maxLines={CHAT_SEARCH_MAX_LINES} className={css.search} />
-line=113:     ctx.slots.register({ name: 'conversation.chat.toolview', key: 'grep' }, SearchRow)
+line=35:   const search = searchCardModel(block)
+line=52:       search={search}
+line=73:     ctx.slots.register({ name: 'conversation.chat.toolview', key: 'grep', locale: NS }, SearchRow)
 expand=… 其余 4 行
 recovery=Found 9 of 42 matches
 
@@ -19,9 +19,9 @@ packages/client/ui-conversation/src/client/contract/search-card-model.ts
 Line 24: export const CHAT_SEARCH_MAX_LINES = 8
 Line 60: export function searchCardModel(block: ToolCallBlock): SearchCardModel | null {
 packages/client/ui-conversation/src/client/toolviews/search-row.tsx
-Line 71: export function SearchRow({ toolName, block }: ToolRowProps) {
-Line 73:   const search = searchCardModel(block)
-Line 90:         <SearchBlock {...search.card} maxLines={CHAT_SEARCH_MAX_LINES} className={css.search} />
-Line 113:     ctx.slots.register({ name: 'conversation.chat.toolview', key: 'grep' }, SearchRow)
+Line 33: export function SearchRow({ toolName, block, inspect, t }: SearchRowProps) {
+Line 35:   const search = searchCardModel(block)
+Line 52:       search={search}
+Line 73:     ctx.slots.register({ name: 'conversation.chat.toolview', key: 'grep', locale: NS }, SearchRow)
 
 (Full grep result stored at: fixture://spill/grep-68. Read it to see every match.)

apps/web/tests/snapshots/steering/mid-steer.expected.md

@@ -19,6 +19,7 @@
   - img
   - img
   - text: Think The user wants me to use the ask_user_question tool to ask them a specific question with the given parameters. Let me do exactly that.
+- text: Running
 - button "Ask question waiting":
   - img
   - img