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.

packages/client/ui-conversation/tests/diff-card.spec.tsx

@@ -253,6 +253,9 @@ describe('FileMutationRow diff card', () => {
       error: { name: 'ToolError', code: 'interrupted' },
     }))} />)
     expect(view.container.querySelector('[data-state="stopped"]')).not.toBeNull()
+    // The amber StateDot is aria-hidden, so ToolRow carries the state to AT as
+    // visually-hidden text; without it a stopped row is a colour-only signal.
+    expect(view.getByText('已停止')).toBeTruthy()
   })
 
   it('renders a plain summary span when the call carries no file path', () => {
@@ -267,12 +270,12 @@ describe('FileMutationRow diff card', () => {
 
 describe('fileMutationToolview registration', () => {
   it('registers one component under both edit and write, and each disposes', () => {
-    const registered: { key: string; disposed: boolean }[] = []
+    const registered: { key: string; locale: unknown; disposed: boolean }[] = []
     const disposers: (() => void)[] = []
     const ctx = {
       slots: {
-        register: ({ key }: { name: string; key: string }) => {
-          const entry = { key, disposed: false }
+        register: ({ key, locale }: { name: string; key: string; locale?: string }) => {
+          const entry = { key, locale, disposed: false }
           registered.push(entry)
           const dispose = () => { entry.disposed = true }
           disposers.push(dispose)
@@ -282,6 +285,8 @@ describe('fileMutationToolview registration', () => {
     }
     fileMutationToolview.apply(ctx as never)
     expect(registered.map(r => r.key).sort()).toEqual(['edit', 'write'])
+    // Both keys claim the conversation locale seat ToolRow's body copy needs.
+    expect(registered.map(r => r.locale)).toEqual(['conversation', 'conversation'])
     // The registrant's inject seam is the load-order contract the row relies on.
     expect(fileMutationToolview.inject).toEqual(['slots', 'conversation'])
     // Disposal removes each contribution (packages/AGENTS.md registry contract).

packages/client/ui-conversation/tests/search-card.spec.tsx

@@ -346,16 +346,18 @@ describe('SearchRow keyed card', () => {
   })
 
   it('registers the one row component under both grep and glob keys', () => {
-    const registered: { key: unknown; component: unknown }[] = []
+    const registered: { key: unknown; locale: unknown; component: unknown }[] = []
     const ctx = {
       slots: {
-        register: (options: { name: string; key: string }, component: unknown) => {
-          registered.push({ key: options.key, component })
+        register: (options: { name: string; key: string; locale?: string }, component: unknown) => {
+          registered.push({ key: options.key, locale: options.locale, component })
         },
       },
     } as never
     searchToolview.apply(ctx)
     expect(registered.map(r => r.key)).toEqual(['grep', 'glob'])
+    // Both keys claim the conversation locale seat ToolRow's body copy needs.
+    expect(registered.map(r => r.locale)).toEqual(['conversation', 'conversation'])
     // One component, two keys.
     expect(registered[0]!.component).toBe(SearchRow)
     expect(registered[1]!.component).toBe(SearchRow)

packages/client/ui-conversation/tests/web-card.spec.tsx

@@ -267,17 +267,19 @@ describe('DetailsPanel web Output section', () => {
 
 describe('web toolview registration', () => {
   it('registers one WebRow under both web_search and web_fetch', () => {
-    const registered: { key: string; component: unknown }[] = []
+    const registered: { key: string; locale: unknown; component: unknown }[] = []
     const ctx = {
       slots: {
-        register: (options: { name: string; key: string }, component: unknown) => {
-          registered.push({ key: options.key, component })
+        register: (options: { name: string; key: string; locale?: string }, component: unknown) => {
+          registered.push({ key: options.key, locale: options.locale, component })
           return () => {}
         },
       },
     } as unknown as import('cordis').Context
     webToolview.apply(ctx)
     expect(registered.map(r => r.key)).toEqual(['web_search', 'web_fetch'])
+    // Both keys claim the conversation locale seat ToolRow's body copy needs.
+    expect(registered.map(r => r.locale)).toEqual(['conversation', 'conversation'])
     // One component under both keys, not two thin rows.
     expect(registered[0]?.component).toBe(WebRow)
     expect(registered[1]?.component).toBe(WebRow)